Robin: Pregnancy?
Marshall: Mm-hmm. Once a mermaid gets pregnant, she becomes a manatee again. Never thought I'd say that sentence.
Future Ted: [v.o.] Wait! That's it! That's what Barney and Lily were fighting about! The Mermaid Theory! But their argument didn't happen at the same time as all this other stuff. I'm literally in the wrong year! It happened much, much later when Lily was... pregnant.
[flashback to Barney and pregnant Lily in the apartment:]
Barney: Well, Lily, I guess it's just you and me. You wanna hang?
Lily: Nah.
Barney: [gasps]
Lily: Whenever we're alone, you spend the whole time undressing me with your eyes. You even take off my shoes.
Barney: High heels chafe my shoulders. But you don't have to worry about that anymore. Ever since you got pregnant, you're just a big fat manatee.
Lily: [gasps] Well, you're a big... stupid octopus face!
Future Ted: [v.o.] That was it! I remember now!
[flashback to Barney and pregnant Lily in the street:]
Lily: Wow. Thanks, Barney. You saved me. You saved us.
[flashback to Barney and pregnant Lily at MacLaren's:]
Lily: If there's one thing you never do, it's call a woman "fat" right to her face!
Barney: I'm sorry, Lily. Hey, you want to see a magic trick?
[Barney puts the beer bottle on Lily's stomach]
Lily: Oh... You're a jerk.
Barney: Hey. Hey, wait. Come on. I was kid... Wait, wait, wait! There's another addendum to The Mermaid Theory. A pregnant woman who's become a manatee can become a mermaid again through one simple act.
Lily: What's that?
Barney: Breast-feeding. Hot.
Lily: Really?
Barney: Really. When those things swell up to three times their normal size, so do I.
Lily: That's so sweet!
Future Ted: [v.o.] See kids? Told you I'd get it!

Future Ted: [v.o.] Kids, in the winter of 2010, we had a new addition to our little group, Zoey. Zoey was married to... The Captain.
The Captain: Boys! Great to see you! Looking smart. Have a wonderful time tonight, okay? Okay.
Marshall: That man is terrifying.
Barney: Everything he said was nice, but I am profoundly scared.
Ted: Keep smiling. He can still see us.

Ted: Hey, guys, Zoey just told me about this great Frank Lloyd Wright retrospective tonight. Who's in?
Lily: Sorry, I'm, uh, I... I- I don't know, washing my hair.
Marshall: Running the water.
Robin: Holding the towel.
Barney: And I'll be home trying to get over the fact that no one invited me to the big hair washing party.

Ted: All right, fine. Guess it'll just be me and Zoey.
Lily: Oh, wait. Just the two of you? Tread lightly, Mosby. Any time a single guy hangs out with a married woman, there are rules that must be followed. Rule number one...
Barney: Don't use the husband's condoms. That's just rude.

Lily: Rule number one: don't go anywhere that has candles.
Marshall: Excuse me, Captain, how do you feel about Ted and Zoey having an intimate chat by candlelight? It'll be the last dinner they ever have.
Lily: Rule number two: No sharing food. Hmm. In fact, anything involving saliva is off-limits. Toothbrushes, thermometers, lipstick.
Ted: Well, if I can't share her lipstick, there's really no point in even going.

Lily: And the most important rule of all...
Barney: Lubricant is public property.
Marshall: Please.

Marshall: Lily's right, Ted. Once you're married, it's very hard to be friends with a single person of the opposite sex.
Robin: Yeah. Unless you're old friends, which is why I can hang out with Marshall whenever I want. Right, Marsh Madness?
Marshall: No doubt, Robo Cop. [fist bump]
Lily: You two never hang out alone. You just made up those nicknames right now.

Marshall: I guess it's true. You and I never really hang out alone.
Robin: Well, let's. Let's have dinner together, just the two of us.
Marshall: Oh! Sweet.
Lily: No candles.
Both: No candles.

Barney: [to Lily] Pur-leez! You lie to your husband all the time. "Uh, uh, that shirt looks great on you", "I love your mom", "I never fantasize about Barney when we're doing it"" Sound familiar, Pinocchio?
Marshall: What's wrong with this shirt?

Robin: [inner monologue] Man, this is awkward.
Marshall: [inner monologue] She's giving me nothing!
Robin: He's just staring at me!
Marshall: She's just staring at me! It's making me nervous. Great, now my left eye is twitching. Marshall, it's cool. She doesn't see it.
Robin: What the hell's going on with his eye? Am I supposed to not talk about that? Great, now my right eye is doing it.
Waiter: Can I get you two some drinks?
Marshall: Lots of drinks.
Robin: Oh, so many drinks.