JOAN Rivers has had endless plastic surgeries, and her fellow comics didn’t let her forget it during a Comedy Central roast in LA the other night, The Post’s Mandy Stadtmiller reports. “You’re like Robo-Cop, you’re half-human and nobody’s given a [bleep] about you since 1986,” Greg Giraldo told Rivers. “You actually have a lot in common with Michael Jackson. You both spent thousands of dollars to look like the Crypt Keeper. You’re both more popular now that you’re dead.” Jeffrey Ross continued: “Joan had a difficult choice to make, whether to do this roast or be the fifth celebrity to die this month . . . Who’s your plastic surgeon? Tim Burton? Oh my God, Kanye’s mom had a better plastic surgeon. Look at her, she’s a cougar. Freddy Cougar!” And quipped Brad Garrett, “Joan has [bleep]ed more old Jews than Bernie Madoff.”