Think about what he was doing the evening before he wet the bed. Caffiene is a bladder irritant, and alcohol is both an irritant and a sedative. Too much of either can cause a person to wet the bed. If it was just one time, and can be blamed on something like too much to drink, don't worry about it. If it happens again, or if you can't figure out what caused it, then a trip to the doctor would be a good idea - it could be caused by a urinary tract infection or something else. If it is caused by too muck to drink and he likes to have a few drinks occasionally, then get some diapers and insist that when he has more than a couple of drinks he wear one to bed. And get good ones, the cheap ones are not much better for night use than wearing nothing.