"Cinderella" joke

Cinderella wants to go to the ball, but her wicked stepmother won't let her. As
Cinderella sits crying in the garden, her fairy godmother appears, and promises
to provide Cinderella with everything she needs to go to the ball, but only on
two conditions.
"First, you must wear a diaphragm."
Cinderella agrees. "What's the second condition?"
"You must be home by 2 a.m. Any later, and your diaphragm will turn into a
pumpkin."
Cinderella agrees to be home by 2. The appointed hour comes and goes, and
Cinderella doesn't show up. Finally, at 5 a.m., Cinderella shows up, looking
love-struck and very satisfied.
"Where have you been?" demands the fairy godmother, "Your diaphragm was supposed
to turn into a pumpkin three hours ago!"
"I met a prince, Fairy Godmother. He took care of everything."
"I know of no prince with that kind of power! What was his name?"
"I can't remember, exactly... Peter Peter, something or other..."