Getting a champ you don't own in ARURF followed by a CTD
ARURF gives sometimes champions you don't own and if the Lobby isn't dodged (Or you don't reroll your pick, like I did this one time) the game will continuosly CTD (Crash to Desktop) until the game is over. Doesn't give a Bugsplat report afterwards either. Just deadass crashes and that's it.