Boy aged 4: Dad, I’ve decided to get married.
Dad: Wonderful; do you have a girl in mind?!

Boy: Yes… grandma! She said she loves me, I love her too… and she’s the best cook & storyteller in the whole world!!
Dad: That’s nice, but we have a small problem there!!
Boy: What problem?!
Dad: She happens to be my mother. How can you marry my mother!!
Boy: Why not?! You married mine!!!!