Haha! It happens to most of us! One of mine actually did get out, I don't even know how. I found him underneath the tank (it's held up on 1" styrofoam blocks to make an air gap for the UTH). Which is good because if he went wandering the cats would definitely have chewed him up. What kind of lid do you have? Are the locks necessary for it to close properly, or are they mostly to keep little kid hands out?