I once had a fourth edition game where the PCs were refugees fleeing from a conquered country, and a small village was willing to take them in if the players killed a group of encroaching goblins. So a young woman opened up her house for the players to stay in, the PCs were a good cleric, and an unaligned wizard.
When the host brought the players food, the cleric decided it was a good idea to rape the young woman, while the wizard sat in the corner reading.
I was taken completely off guard , and only forced an alignment change, needless to say his actions also perverted how my players and I felt about playing this game, and it died soon afterwards.
We kicked the rapist out of our group a week later, and he has returned to play World's Largest Dungeon, after a year of exile.