True Story:

One of my old boyfriends used to keep two hamsters in his room. They were both quite old by the time he and I got together so we both understood that their end was imminent. One of them sported a large hairless bulge on his back and so was known as Tumor. Eventually Tumor did meet his end, but not in the way we thought it would happen. The old boyfriend came home from school one day to find Tumor bits all over the cage and the other hamster cowering in a corner. When they went to the pet store to get a new hamster they asked the guy behind the counter about the incident. He said "sometimes old hamsters just explode."