A person laughs every day.
"Man," they say, "I'm glad I'm not an egg, otherwise I'd just CRACK MYseLf uP!"
Listen up, buttercup. This joke is egg-cellent because it hinges on a pun. "Crack myself up" sounds like "laugh hysterically," but also refers to literally cracking an egg. You're so dumb that you're probably chicken-brained.
Gwen
Well you sure cracked me up!