Mommy, mommy! Are we liars?
"Shut up and cross your fingers when you say that."
Okay, so basically, the kid asks his mom if they're liars. And the mom is like, "Quiet! And cross your fingers while you answer that question." It's funny because crossing your fingers is what people do when they're telling a lie! Get it? You probably don't, since you think pineapple belongs on pizza.