joke copyright
Your jokes are protected by copyright if they are original and contain some amount of creativity. Generally, very short jokes and one-liners probably won't be protected. The more intricate the joke, the more likely protection. Assuming a copyright, you will have to show access to your work unless they are pretty much the same (which you say they are). To sue, you will have to regsiter, if not already done. You should consider if the expense is worth the damages you could receive (what you lost and what they gained or maybe statutory damages). If you think so, you should hire an attorney to file suit. If they won't take it, it is probably not worth your time (at least from a money view).
