A few days ago I was talking to some friends, and friends of those friends, at a bar.
I decided to break the ice with the new friends with a few jokes, most of which went down very well...until I decided to tell a few more offensive ones...and picked the worst possible one to start with.
Here's the joke I told:
"What do you do if you see an epileptic having a fit in the bath?
Throw your washing (laundry if you're American) in."
One of the new friends instantly became enraged and swung for me. When I asked him what the hell his problem was he replied that his younger brother was epileptic and died in the bath many years ago.
Obviously I felt mortified as I didn't know about it, and said "I'm so sorry to hear that. Did he drown?"
"No," replied the guy. "He choked on a sock."