Your ex boyfriend ;)

It means that he's really mean. Exact dictionary translation: a contemptible obnoxious person. "He's so mean!" can be changed to, "He's such a jerk!" Hope that helped...

It means that the man is unpleasant, rude, inconsiderate, or anything else that is negative. You use it to describe someone you don't like.

Whenever a friend says something to you teasingly and you would reply "讨厌！" it often is also fitting to say, "You're such a jerk." My friends and I use this phrase all the time when teasing each other.

I suggest you don't use this expression... it's very impolite. Maybe the man (or woman) is a jerk, but that does not mean that you have to be impolite. You could simply say "He/She is not polite / He/She is impolite". Just my suggestion...