Daily quests. I'm trying to get the Kite mount that requres you to get exalted with a bunch of MoP factions, so I've been running all the dailies for those factions.

And then it never fails that I get up to take a piss or refill my drink at some point and come back to "You have been removed from the queue because you did not accept the invitation." I guess when time in queue is 32 minutes with average wait time of 22 minutes, you're just asking for it if you step away for a second at that point.