Marshall: Another guest? Who could this be? Why, it's Lily! And she's here to deliver one of your requests!
Barney: Oh, thank you, Marshall.
Lily: Oh, not that one.
[flashback to ten months earlier:]
Barney: An appearance by my all-time idol, the Karate Kid!
Future Ted: [v.o.] The Karate Kid was an uplifting '80s classic about a teen, played by Ralph Macchio, who defeats the local jerk, played by William Zabka. At least, that's how most people saw it.
Lily: Here he is, just as hot as when his Tiger Beat photo spread gave a young girl the courage to explore the suddenly unfamiliar topography of her changing body... the Karate Kid!
Ralph Macchio: Hey, Barney. It's Ralph. Listen, it's always flattering...
Barney: No! I hate Ralph Macchio! I hate him, hate him, hate him! He is not the Karate Kid! The Karate Kid was William Zabka, star pupil of the Cobra Kai Dojo, who this monster defeated with a cheap, illegal head-kick in the most tragically haunting film ending of all time.
Ralph Macchio: Oh, see, I thought you meant fun-crazy.
Barney: Shut it, Ralph Macchio. Why don't you go have a party with Luke Skywalker and Harry Potter and War Horse and all the other movie bad guys and stop ruining mine!

Lily: Wow, Barney, it looks like your mom kept your childhood bedroom just the way you left it.
Marshall: Yeah, that sure is a big poster of The Karate Kid above your bed.
Barney: Hey, Karate Kid's a great movie. It's the story of a hopeful young karate enthusiast whose dreams and moxie take him all the way to the All Valley Karate Championship. Of course, sadly, he loses in the final round to that nerd kid. But he learns an important lesson about gracefully accepting defeat.
Lily: Wait. When you watch The Karate Kid, you actually root for that mean blond boy?
Barney: No, I root for the scrawny loser from New Jersey who barely even knows karate. When I watch The Karate Kid, I root for the karate kid: Johnny Lawrence from the Cobra Kai dojo. Get your head out of your ass, Lily.

Barney: What could you possibly have to say for yourself?
[flashback to Ted and Margaret talking about acting tips:]
Margaret: Acting rule number one: "Don't be afraid to improvise."
[present:]
Ted: Was it me who betrayed you, or you who betrayed me?
Barney: I'm sorry. What?
[flashback:]
Margaret: Acting rule number five: "Invent a rich back story for your character."
[present:]
Ted: November 14th, 1998. The overnight train to Monte Carlo. I was in the billiards car hustling some Algerians out of few thousand dinar, when you seduced my fiancee! Who is blind and thought you were me.
Margaret: Yes.
Barney: What in God's name are you talking about?
[flashback:]
Margaret: Acting rule number eight: Don't be afraid to get physical.
[present:]
Ted: [slaps Barney] You know damn well what I'm talking about!
Barney: No, I don't!
Ted: [slaps Barney again] Yes, you do! And by God, I'll hear you say it, scoundrel!

Lily: Wow, Barney, it looks like your mom kept your childhood bedroom just the way you left it.
Marshall: Yeah, that sure is a big poster of The Karate Kid above your bed.
Barney: Hey, Karate Kid's a great movie. It's the story of a hopeful young karate enthusiast whose dreams and moxie take him all the way to the All Valley Karate Championship. Of course, sadly, he loses in the final round to that nerd kid. But he learns an important lesson about gracefully accepting defeat.
Lily: Wait. When you watch The Karate Kid, you actually root for that mean blond boy?
Barney: No, I root for the scrawny loser from New Jersey who barely even knows karate. When I watch The Karate Kid, I root for the karate kid: Johnny Lawrence from the Cobra Kai dojo. Get your head out of your ass, Lily.

Barney: And then my mom got better. Which was miraculous. But it meant that I had to keep "Betty" around and cast a kid to play my son, Tyler.
Lily: This is crazy. You actually cast your own son?
Barney: Well, for a while, I got by borrowing/babysitting my neighbor's baby. And this one Christmas, when my mom was plowed on eggnog, I got away with a bag of flour and a Chuckie mask. But eventually, I had to hold auditions.
[flashback to Barney in a room of aspiring child actors:]
Barney: Four, eight, thirteen, you can stay. The rest of you may go.
Stage Mom: You said that if I slept with you, my son would get the part.
Barney: Well, apparently, I'm a better actor than your kid. Bring in the 11:00's!
[present:]
Barney: And that's how the role of Tyler eventually went to... Grant.
Ted: Come on, Grant seems pretty good.
Barney: You think so? Watch this. Hey, Tyler. [the kid is unresponsive] Tyler. Tyler. Grant.
Grant: Yeah?
Barney: See? It's like amateur hour over here. Call me crazy, but child actors were way better back in the '80s.