We had a hamster. Evil thing it was.
One time we threw a Halloween party and we and some mates crashed in the lounge for the night and we were awaken by some rustling.
The hamster had escaped and gone into the kids trick or treat bucket and was munching on the chocolate.
After we disturbed it, it ran out the bucket into the hallway, then shimmyed up the narrow gap between the wall and the table where it's cage was, and then, I **** you not, it climbed back into it's cage and pulled the trap door thing completely locked closed.
The next time we cleared it out we found pasta and all sorts in there so he must have done it loads of times.