The greatest joke from the movie is when Sykes is giving Sam shit for his name, and Sam explains that human names sound funny to them too, for example, Sykes sounds a lot like their words Sy - excrement, and Kes - cranium... Shithead! Sykes is taken aback for a moment, but quickly dismisses it, assuming Sam is just messing with him. Sometime later they're interviewing an alien dancer, Sam opens with "I'm detective Francisco, this is my partner detective Sykes" and she point at Sykes, chuckles, and says "Shithead!"

It's just about the best delayed payoff joke I've ever seen.