(adj.): normally used in reference to a party, get together or any mutual gathering of people; when a otherwise tame and normal get together quickly degenerates into a complete and utter shit show/disaster due to an inundation of loud, obnoxious or otherwise uninvited partiers, frat boys/sorority girls or bros/biddies who "heard about a totally sweet party going down from my friends".
Michael: Hey dude, so what's the condition of that little party Nick was having? A few of us were thinking of stopping by for a bit.
Richard: Don't even waste your time man, this whole place went cherbrobyl about an hour ago. I have no idea how I'm going to get out of this place (sob).