Tips for getting out of handcuffs?

Okay, a "friend" of mine recently played a really mean trick on me & my best friend. We came up with a way to get her back, but it sorta backfired. What we did is purchase a set of magic handcuffs, the kind your supposed to be able to open without a key. We cuffed ourselves together and approached our friend. We intended to perform the trick and free ourselves and then ask her to let us try it out on her. We were then gonna lock her wrists together and leave her like that. Only problem is, we couldn't perform the trick and we can't seem to find the key, so we're stuck. We don't want anyone else to find out about this, so can anyone help us figure out what we did wrong before my parents come home?