Peggy

Okay, so listen up, buttercup. The joke is that the dad named his daughter "Peggy" because she doesn't have legs, and "peg leg" is a wooden leg, get it? It's funny because it's kinda dark but also a play on words. You probably think a "play on words" is what you do when you write "See you later alligator" to your girlfriend, who is a lizard. You are so dumb.