My Luck

Sylvester Stallone, Arnold Schwarzenegger, Chuck Norris, Ron Jeremy.
I know who Sylvester Stallone, Arnold Schwarzenegger and Chuck Norris are. I have probably seen 90% of their movies. I am not familiar with Ron Jeremy. I thought that the joke might be that there was something common about all 4 of them. I know I could look up Ron Jeremy, but he isn't familiar.