(The episode starts at the Park's house with Mordecai, Rigby, Muscle Man, Starla and Margaret driving back from pizza.)
Rigby: Ah, stuff so good.
Muscle Man: Mama mia.
Starla: Thanks for driving.
Margaret: Yeah, no problem.
Mordecai: Man, who knew pizza can be so good.
Margaret: Uh, that's kinda it's thing.
Rigby: Go, go, go. (Rigby, Muscle Man and Starla rush towards the window to watch Mordecai and Margaret) Shh, Shh. Come on, come on.
Muscle Man: No way man. No way.
Rigby: Here it comes. (They watch as Mordecai and Margaret awkwardly hug.)
Muscle Man, Starla, and Rigby: Ugh!
Rigby: Ugh, man! Ugh!
Muscle Man: Told ya.
(Muscle Man, Starla and Rigby sit on the coach, when Mordecai comes back inside, they stare at him)
Mordecai: So, what do you guys wanna do... now? What?
Muscle Man: That was painful, bro.
Mordecai: What was?
Rigby: That. Uh, uh. Uh.
Mordecai: You guys were watching me!? Ugh, geez.
Muscle Man: Dude, bro, when are you gonna seal the deal? You've been like wanting to kiss Margaret for years now.
Rigby: This is real talk.
Mordecai: What? What do you guys know? I'm just...waiting for the right moment.
Muscle Man: Bro, you gotta make the moment. Watch. (To Starla) Did you have fun tonight, babe.
Starla: I always do.
Muscle Man: I hope you saved room for desert.
(Muscle Man and Starla make out)
Rigby: Hmm, seems simple enough.
Mordecai: Ugh, you guys don't get it! It's not easy for me. I try.
Mordecai: I mean, I've had some chances in the past that didn't work out, but it's just gotta feel right, you know. Uhh, I don't know. I don't know what's wrong with me.
Muscle Man: Sounds like you need some extra excentive, bro.
Mordecai: Yeah, like what?
Muscle Man: Hmm. (laughs) Okay, it's Sunday. If you kiss Margaret by midnight Friday, I'll wear a diaper for a whole week.
Rigby: Whooa, now we'll talking!
Mordecai: Alright, I can do that.
Muscle Man: But of course, if you don't kiss her, you've gotta wear the diaper for a whole week.
Mordecai: Aw, what? I don't know. This is probably the dumbest idea I've ever heard.
Muscle Man: Hey, you already want to kiss her, right? So all you gotta do is kiss her. Then you can laugh at me in a diaper. It's a win-win, bro.
(Mordecai looks at Rigby and Starla. They are smiling and moving back and forth.)
Mordecai: Alright, I'll do it.
Muscle Man: Whooo! Aw, man! I got you good! (laughs and jumps on the table) You'll gonna wear a diaper for a week! He's never gonna do it! He's never gonna do it! Diaper time! (laughs)
Starla: Your so bad.
(Starla and Muscle Man make out and leave)
Rigby: Whoa ho ho! Betting big time huh?
Mordecai: Pff. It's no big deal. I just have to kiss her. Oh no! I have to kiss Margaret before mid night Friday!
(The next scene shows Mordecai and Rigby at the Coffee Shop)
Rigby: Dude, we've been here for an hour. You gonna ask her out, or what?
Mordecai: I'm working up to it. Here she comes. Act natural. (Slurps an empty glass)
Margaret: Hey guys. Dude, that glass is empty.
Mordecai: (laughs nervously) Oh yeah, it is. So, do you want to hang out tonight?
Margaret: Like a date?
Mordecai: Yeah, like a hangout, or chillsesh, whatever you like to call it.
Margaret: Sorry, I can't.
Mordecai: I mean, it could be a group thing too.
Margaret: No, I mean I can't tonight, I have class. I'm free Friday night though.
Mordecai: Sure, sounds great.
Margaret: Cool. See you then. (She leaves)
Mordecai: See ya.
Rigby: Dude, Friday!?
Mordecai: Ugh! The bet would practically be over then.
Rigby: Yeah man. And if that date was awkward like that conversation was, Margaret's never gonna let you kiss her.
Mordecai: It's cool. It just means I've got time to get ready.
(While "You Might Think" is playing, the next scene starts off on Monday, where Mordecai is getting some exercise, with Rigby cheering him on, and Muscle Man buys every bags of diapers at the store. Then on Tuesday, Mordecai is at the store buying mints, and magazines about how to kiss, and while he practices, a woman gives Mordecai her phone number. Then on Wednesday, Mordecai is getting a haircut, then after that, when Mordecai is finding something cool to wear, he finds all the bags of diapers that Muscle Man bought in his dresser. Then on Thursday, Mordecai does some push-ups, with Rigby timing him, and then we see Mordecai getting a free massage, and getting a tuxedo, and when he had to pay $1,500 for it, he just runs away. Now it's Friday, and Mordecai and Rigby are outside, with Mordecai wearing a shirt a tie and a fanny pack on his waist)
Rigby: Big night, dude. How're you feeling?
Mordecai: You know, I'm actually feeling pretty good.
Rigby: That's good. But I do have one piece of advice.
Mordecai: You gotta pack a mint, bro.
Rigby: That's what I was gonna say. How did you know?
Mordecai: Pff. Everybody knows that. (unzips his fanny pack to show Rigby whats inside) I got it covered. Mints, gum, strips, breath spray, toothbrush, floss.
Rigby: Remember, you got till twelve tonight.
Mordecai: Wish me luck. (He leaves)
Rigby: Good luck.
(Muscle Man comes out)
Muscle Man: Think he'll really do it?
Rigby: Not a chance.
Muscle Man: Wanna follow him?
(Rigby gets in the golf cart with Muscle Man and they start to follow Mordecai laughing)
(Mordecai is at Margaret' apartment, and rings her doorbell, and while he waits, he takes a mint. Margaret comes out wearing high heals and a yellow dress)
Margaret: Hey, Mordecai.
Mordecai: Hey. You look nice.
Margaret: Thanks, you too. Should we get going?
Mordecai: Ye-yeah. (opens the car door for Margaret) Your chairette, m'lady.
Mordecai: Thanks again for letting me borrow your car.
Margaret: Hey, it would be nice having you to drive me around for a change. Makes me feel special.
Mordecai: (laughs) Yeah. (he drops the key and when he tries to get it, he accidently honks the horn)
Margaret: You nervous about something?
Mordecai: (laughs) Why would I be nervous?
(Now Mordecai and Margaret are at the movie theater)
Margaret: Oh man, I haven't seen a movie in forever. What do you see?
Mordecai: How 'bout Oopsie Daisy?
Mordecai: Oopsie Daisy. You know, starring Jannie Rachel as Daisy? The woman who meets the perfect man--?
Margaret: (gasps) "Bucktooth Bob Goes to Europe"! I didn't know it was out yet! Come on, we have to see it, I love Bucktooth Bob!
Mordecai: Really? But I thought we see Oopsie Daisy. It's got a heartwarming story, some romance.
Margaret: Boring! Come on, let's have some laughs.
Mordecai: (reluctantly) Two for "Bucktooth Bob Goes to Europe".
Bucktooth Bob: Man, what the heck is this? A boot washer? (Everyone but Mordecai laugh. Mordecai then takes a whole bag of mints, and then he holds Margaret's hand, and they stare at each other) What do you call this place?
Man in movie: The Eiffel tower. (slips on a banana peal)
Bucktooth Bob: "I-fell" tower? More like "He-fell" tower.
(Everyone but Mordecai laugh again. Then Mordecai notices that Rigby and Muscle Man are behind him, and Muscle Man shows Mordecai a diaper)
(Then Mordecai and Margaret exit the theater)
Margaret: Ah, oh my gosh, my stomach. It hurts. That was so good.
Mordecai: Yeah, ha.
Margaret: I had a really great time tonight, Mordecai.
Mordecai: Yeah, me too.
Woman: I had a really great time tonight. (she and her boyfriend kiss, along with other couples kiss)
Margaret: Ugh, like get a room, right?
Mordecai: Yeah, ha.
Margaret: Well, I guess it's getting kinda late, so--.
Mordecai: What? No, no, it's only 11:2--. 11:25!?
Margaret: Yeah see, so maybe I should go.
Mordecai: No no. Come on, I'm having too much fun.
Margaret: Oh yeah?
Mordecai: Yeah. Look, there's one more place I need to take you.
Margaret: Alright, I'm game. (Mordecai takes Margaret back to the park's lake) It's beautiful!
Mordecai: Yeah, this is one of my favorite places in the park.
Margaret: Let's go sit by the water. (gets out of her car)
Mordecai: Sure. Just one kiss. You can do this. (Muscle Man and Rigby spy on Mordecai) Just--. Ahh! What are you guys doing?
Muscle Man: Six minutes till diaper time, bro. You gonna make your move, or just keep talking to your reflection all night?
Mordecai: I was just about to do it.
Margaret: Mordecai! You coming?
Mordecai: Yeah, just a sec.
Muscle Man: Better get out there.
(Mordecai gets out his fanny pack from the glove compartment)
Mordecai: Right. This is gotta be perfect. (he chews up all the gum, takes a lot of mints, and spots Margaret putting on lipstick. Then he gets nervous, and takes a couple mint strips)
Muscle Man: I think you're good, bro.
(Then ice come out in the car)
Rigby: Uh, seriously dude, you should stop.
(Then, Mordecai sprays some breath spray, then he feels sick and a minty breaze comes out of his mouth, creating a winter wasteland)
Rigby: What happened?
Mordecai: (coughs) Hey, where you going?
Margaret: It got really cold all of a sudden. I think we should go back. (Margaret tries to open the car door, but it's stuck) Ugh, it's frozen shut.
(More ice comes on the car, and Muscle Man comes out)
Muscle Man: Aw man! We gotta get outta here!
Rigby: But got to see if he does it!
Margaret: Muscle Man? Rigby? What are you guys doing here? And see who does what?
Muscle Man: You better tell her about the bet, bro.
Margaret: Bet? What bet?
Mordecai: Uh, well see, it wasn't a bet persay. I just said I would kiss you by Friday at midnight, and if I didn't, I have to wear a diaper for a week.
Mordecai: See, but if I did kiss you, then Muscle Man would wear the diaper, so yeah, it was pretty much a bet.
Margaret: So you bet Muscle Man that you could kiss me!?
Rigby: Well, it was more than he would kiss you, not could.
Margaret: QUIET, RIGBY! I can't believe you, Mordecai! Here I thought we were having a great time on a fun date, and it was all for a dumb bet!?
Mordecai: Yeah, but--.
Margaret: Ugh! (she runs off)
Mordecai: Margaret, wait!
Muscle Man: Nice going, bro.
Mordecai: Ugh! (runs after Margaret) Margaret! Margaret! Your gonna freeze out here!
Margaret: (off-screen) I don't care!
Mordecai: Look, I'm sorry, okay? I'd wear a diaper for the rest of my life if only you forgive me for how dumb I was being.
Margaret: (off-screen) What is wrong with you? You always do this. Everytime it seems like we're getting so close, you throw me for a loop.
Mordecai: I don't know what's wrong with me!? (his foot starts to get frozen, but breaks it) It's just that, (his other foot gets caught) you're like one of my best friends, and (he breaks the ice off of his foot) I get all weird when I'm around you. (Both of his legs get caught in ice) Sometimes I don't know what to do about it.
Margaret: How 'bout you start being honest with me? That would be a good start. And you better talk fast.
(Mordecai's entire body but his head gets trapped in ice)
Mordecai: Yeah your right, okay. Look, I really just wanted this kiss to happen, and I lost sight of being a good friend. And the only reason I took the bet was to give me extra confidence to go through with it. Which, didn't even work anyways, but really it's all because, I LIKE YOU!
Margaret: What time is it?
Mordecai: Who cares?
Margaret: No, really. What time is it?
Mordecai: (tries to break the ice off of his left arm and checks his clock) 11:59.
(Margaret holds Mordecai close)
Muscle Man: Oh my gosh! No! No!
(The ice starts to melt and Margaret closes her eyes and leans in to kiss Mordecai. Mordecai's eyes sparkle, and he puckers up, and when they are close to kiss, Margaret dodges it, and whispers in his ear)
Margaret: Have a nice week, diaper boy.
(The next scene shows Mordecai wearing a diaper while mowing the lawn in a circle, while Muscle Man, Rigby and Starla are laughing and Muscle Man is trying to take a picture of it on his phone)
Muscle Man: Aw man! This is too good. Wait, why's he smiling? YOU'RE RUINING MY PICTURE!
Rigby: Yeah, why you so happy!?
Mordecai: I'm happy cause I realize Margaret was actually having a great time on the date, and that means she must like me. Which means, that I have a chance to kiss her one day.
Rigby: You mean we have to keep waiting and waiting to see if you will do something about it?
Mordecai: Hey, it's gotta be the right moment.
Muscle Man: I bet you he never does it.
Rigby: You're... on.
The End of " Do or Diaper"