The name for someone who pretends to be Jewish, just for the days off work.
Coworker #1: Did you see Mike at work this morning?
Coworker #2: Nah, bro, it's Yom Kippur.
Coworker #1: Oh, I didn't realize he was Jewish.
Coworker #2: Well, he's just a Feignstein. He's actually Irish Catholic, but don't tell anybody.