from a fellow magician 
(though i mostly do street stuff: cards, coins, money, that type of deal)
Looking at improving the shazaam effect, master combination locks (like the ones that are used on the lockers all the time) are a walk in the park to shim, super quick and very easy, and there is no way you could have possibly "picked" it... in fact, you can have your audience open the package to convince them that you dont know the combination and are not dialing it using a pair of eyes in the back of your head... and you could give the lock away as a souvenir (especialy if you are performing for a larger audience...)
Oh, have you played with hand cuffs much? I used to play the get shackled then sneeze (and close your mouth with your hand) thing in middle school (after i saw some magician do it on TV), then immediately turn around and have your hands still shackled then turn around again and ask the audience how long they think it will take you to decuff, and while they are giving you answers, point at the lowest time (or the cutest girl), say they were the closest and present a set of fully unlocked cuffs in your other hand. (aaah the good old days when people thought hand cuffs were seriously secure...)
btw the only reason i knew how to open that lock was because hand cuffs use the same type of lock i used to have on my desk at home, and i used to loose keys for that all the time lol, so a paper clip and 3 seconds of time... speaking of which, i lost the set of cuffs too, years ago...
Actually that's what got me interested in locks, and now lock picking..... and magic...
