noun. An email hazard that is particularly common among people the medical profession calls "fucking idiots".
Real citation: "There is a Reply-To-Allpocalypse happening at work. So far 70 emails strong..."
(Sept. 23, 2009, Kristina Millar, Twitter, http://twitter.com/kjmillar/status/4314457650)
Made-up citation: "Today's reply-to-allpocalypse was a real bummer... Then again, maybe one of my co-workers will know how to get stubborn stains out of a testicle."