My gym locker requires me to have a small lock, that I carry in my backpack. After (presumably) leaving the lock unlocked in my backpack and it shuffling around, it is now closed with a different combination that the one I had previously set it up with.
Since it's only 3 digits, I manually tried 000-130 and 970-999 until I gave up. Having wanted to learn lock picking for a while, I just youtube'd how to open a 3-digit lock and it was surprisingly easy.
Just start with the top dial and rotate it until you feel it click. Then do the opposite dial, then the middle one. With just a tiny feel for the pull, you can unlock it in 30 seconds. Tells you how good they are at providing safety.