It's Always Sunny in Philadelphia, Season 3

Dennis:
Some gay guys are twinks, and others are bears. This gay guy's a bear. By the way we're totally cool with that. To each his own.

Frank:
Wait, I'm a little confused here. What's a twink?

Dennis:
A twink is small and slender, like Mac.

Mac:
Oh no, I'm too muscular, I would be a bear.

Dennis:
Ohh don't think so bro. Not hairy enough.

Frank:
Smooth. I would be a bear.

Dennis:
No no, see I don't think you'd be a bear either. As a matter of fact, I don't know what you would be, because you're definitely not a twink.

Frank:
I'd be a top, that's for sure.

Mac:
Can a twink be a top, or is that reserved for bears?

Dennis:
I'm sure there's a great deal of switching back and forth, but I think more often than not bears are tops, unless they happen to be power-bottoms.

Frank:
What's a power-bottom?

Mac:
A power-bottom is a bottom that is capable of receiving an enormous amount of power.

Dennis:
Actually Mac, you got it backwards. See, a power-bottom's actually generating all the power by doing most of the work.

Frank:
Does the power have to do with the size or the strength of the bottom?

Mac:
Now Dennis, I've heard that speed has something to do with it.

Dennis:
Speed has everything to do with it. You see, the speed of the bottom informs the top how much pressure he's supposed to apply. Speed's the name of the game. Right, buddy?

(notices that Corporate Guy has left)

Mac:
Goddammit!