There was this boy in high school that was what you would consider a nerd. Anyway he had his own lab in the basement of his home and one night he came up and said "Dad look what I made." So he poured a flask of fluid into a pot of soil and instantly grass started to grow.
Of course his dad was really impressed with this and asked his son if he can make something to make his penis grow.
His son thought for a minute and said that if he did then dad would have to buy him a convertable.
Dad agreed.
The next night the son came out of the basement and gave his dad a vial. The next morning his father came to him and told him that he had something to show him. They went to the front yard and the boy saw a cherry red ferrari.
The son looked at his dad and said "I only asked for a convertable."
The dad replied "the convertable is in the garage. The Ferrari is from your mother."