While "Turning in a Quest" is a common term for turning in and accepting a reward for completing an in game quest it is also used as a term to excuse ones self to use the bathroom. When leaving your keyboard to take a bathroom break it is common to tell group members that you have to "Turn in a Quest". It started as a joke among the guild "Raiders" on the Tanaris realm, and spread to other members becoming a more commonly used term.
"Be right back guys, I have to turn in a quest."
by mrphy42 February 16, 2007