Sam: Let's, uh... Wait a second. I don't get something here. Now, if it's not your kid, how come Maggie's coming in here and calling you "Daddy"?
Cliff: Uh, that's easy. She's setting up a trap for me. All right, put yourself in the frame of mind of the female psyche. Now, she goes off, gets herself pregnant, looking for a husband, provider, best friend, lover. Okay? First name on top of her wish list.
Sam: ... Cliff Clavin?
Cliff: Bingo.