A man having trouble achieving an erection decides to consult a witch doctor.
The witch doctor throws some herbs on a fire, shakes his rattle, and says, "I have placed a powerful spell on you, but it will only work once a year. Just say 'one, two, three' and you'll get the largest erection you've ever had. After your wife's been satisfied, simply say 'one, two, three, four' and it will disappear for 12 months."
Later that night as the man is lying in bed watching television, he says to his wife, "Watch this! One, two, three!" His penis becomes larger and stiffer than ever before. His wife is amazed. She smiles and says, "That's great! But what did you say 'one, two, three' for?"