Anyone who's ever owned a hamster knows that you must enter this new relationship with the understanding that these little guys can literally disappear at a moment's notice.
They're unbelievably small, unbelievably fast, and unbelievably unwilling to be kept in a cage all day, no matter how lovingly you've prepped one for them. At some point or another, most hamsters manage to get their taste of sweet freedom and have no intention on ever coming back.
Now, that being said, losing your own hamster is one thing — losing someone else's is a nightmare.