Sister Looks Like Santa Claus

Okay, listen up, smoothbrain. This joke is pure anti-humor. It sets up expectations with the comparison to Santa Claus, but then hits you with a punchline that makes absolutely no sense in context. 'No, too many people!' is just a random statement. The joke is funny because it isn't funny in a conventional way, and you, trying to figure out the logic, are just proving how simple you are.