You find an old Masterlock combination
lock from years ago lying around. You need to use it, but you have no idea what the combination
is. You of course would not pencil
it on the back -- then anyone could open it. So what
the heck do you do?
If it's one of the traditional black with white numbers Masterlocks, it works beautifully. Take a black sharpie and start randomly blacking out the white paint -- but careful, not too much. Do not, at this point, completely black out any post! This is important! The goal here is to make the lock look like one of the old, worn out locks that are in locker rooms. Make it look like the paint has just worn off pretty badly. Now do this -- subtly! Completely black out the little dash of the three numbers that are the code for the lock. leave the number, black out the little post you're supposed to align with the arrow. If you want to make it look more properly worn, nearly (but not completely) black out the posts on either side of this one. Go back and reapply sharpie where it's needed, to make the completely-blackened posts inconspicuous. Now, whenever you pick up this lock, you have to try, at most, six combinations, from the three numbers, instead of every number set possible. Not bad, huh?
I actually came across a lock I did this to, from 5 or 6 years ago, was able to interpret the marks, and opened it with no problems. It really does help. Now I just need to make sure none of you ever get near my padlocks...