Friend 1: How come when you say "apart" your lips move apart, but when you say "together" they move apart?
Me: Maybe your lips want a divorce.
Listen up, buttercup. This joke is all about how the words "apart" and "together" make your lips move apart when you say them. The punchline is that maybe your lips want a divorce, which is a funny way of saying they don't want to be together anymore. You probably get divorced a lot.