Louis C.K. has really crossed a line now.

Anthony Jeselnik says that Louis stole the setup to some of his jokes.

During a Q&A at the 92nd Street Y this week, one-liner specialist Jeselnik said that “years ago” Louis had watched his show at the Comedy Cellar from the wings, and when Jeselnik came offstage, CK said to him, “I love watching you because I try to guess your punchline, and I come up with my own that works, but it’s different from yours.”

Jeselnik said that Louis — who was due onstage next — then asked him if it would be OK if he tried some of his own punchlines to Jeselnik’s setups on the same crowd for fun. Jeselnik said he told Louis it would “be an honor” but he never expected CK — who is trying to make a comeback following the scandal over his sexual misconduct — to keep using his material.

Jeselnik added, “I see him six months later at the Aspen Comedy Festival — and he’s doing the f - - king jokes!”