It hasn't happened to me yet, but a friend of mine forgot to put the top on to his boa's tank. Later she was found under his bed in a family sized potato chip bag (This was when she was still quite a baby and was only 4 feet in length). After that day he has learned to keep his room clean because it literally took us a whole day to figure out where the boa went, plus she got a boo boo on her from trying to slither across that dirty floor