One night, little Johny saw his parents having sex and didn't know what they were doing.

The next day, Johny asked his older brother what it was that he saw last night.

His brother, not wanting to have the sex talk with his younger brother, said "Oh, they were just making cakes."

The day after that, Johny went to his older brother and said "You know how mom and dad were making cakes last night? Well, I licked off the icing."