If you ever forget the combination to your bike lock, here's how to open the lock -- without any tools required. A word to the wise: You might also consider getting a more secure kind of lock for your bike.
The video shows how to open a standard four-digit bike combo lock by looking for the gaps between the numbers.
Obviously you should only use this hack for your own lock (and not for stealing bikes). It's a good idea to learn about lock picking of all kinds to increase your security knowledge.
How to crack a combination bike lock in under 30 seconds [WonderHowTo via Reddit]