In the prank section of the magic shop, you find a dicking wand. The wand has the following instructions:
"Play a joke on your friends. Point this magic wand and say, 'Hardy Har Har'. Your friends body will disappear and all that will be left of him is his dick and balls.
Point the wand at your own genitals and say, 'Man's best friend' and the person closest to you will become your dick and balls.
Point the wand and say, 'dickhead' your friends head will become a dick.
(The instructions continue listing different things that can be done with the wand.)
All transformation spells wear off as soon as the transformed has an orgasm."