Making Cake

A young boy and his dad go to the beach and there is a couple making out, so the boy asks his father what they are doing.

His dad replies, "They're making a cake."

The boy says, "Oh." The next day they go to the zoo and there are two monkeys getting it on and a the boy asks his dad, "What are they doing?"

His dad replies, "They're baking a cake." So they go home and the next day, the boy says to his dad, I know what you and mom were doing last night, you were baking a cake." The father asks the boy, "How do you know?"

The boy replies with a big grin, "Because I licked the frosting off the sheets this morning."