I had one of those guys, too. In the middle of Naxx 10 man he went "afk, bathroom". Well, a person's gotta do what a person's gotta do. About 6-8 minutes later he came back and was like "Sorry, I didn't find a towel at first" "...What`?" "Well, I went showering." We thought he fell into the toilet, but that's a little ridiculous. Became a running gag, too.