I know 4 ENTP's (they all have personality disorders... go figure) and I've noticed that they have an extremely hard time admitting when they're wrong and will tell you that you're wrong for argument's sake. These are two things that bother me VERY much. Actually, the latter isn't too bad if you could simply clarify that you're making the argument for argument's sake, otherwise it just gets awkward and pointless.
My last girlfriend is an ENTP and she always poked fun at me when I was feeling vulnerable, which was funny at first because I have to laugh at myself sometimes, but when I tried to do the same to her she would get extremely defensive and attack me verbally. Don't dish it out if you can't take it in return.
I always get the feeling that they are analyzing my every action. It's like they can read me like a book.