Hand scanner
I think there are a lot of things we can cheat at, you can learn how to cheat craps, but it seems to me that cheating a scanner is almost impossible. Anyway, maybe the method above can work.
Recently, my management implemented a fingerprint scanner based attendance system like this one http://www.minutehound.com. Which is very unpleasant for all us (employees) now they’re watching all are steps. So I did made a small research and found couple of methods to cheat it, that would require to make a copy of your fingerprint from some material and ask your friend to sign you in)