That depends on the fucking joke.

How long is a piece of string?

See how stupid the question is?

some point after the punchline?

or if you are joking about the jews...that would qualify as being anti semtic and totally unacceptable

When people get hurt. .

when people start hitting each other...or get in a fight...

As soon as your joke was only a joke in your mind, and wasn't to others. Typically when the majority of people wouldn't laugh.

Everyone has a different definition of 'too far'. Some people are more tolerant and less sensitive than others while some people do not take jokes very lightly. It all depends on the person, in my opinion. Personally, I am quite comfortable with jokes of any kind except for jokes about serious illnesses. I am also not a fan of ill-intentionally racist jokes.

When the content of the joke is about something tragic that has recently happened, then it should be off limits. Such as a 9/11 joke before the bodies are even cleared from the wreckage.

One can joke about the government's handling of it, the engineer of the building, but leave the victims out of it. They should be forever off limits.

Im a huge fan of dark humor. I understand alot of the stuff I laugh at can be offensive to someone. I really don't get offended easily but I know some people do so i try not to make those kinds of jokes.