Shaming a person who is the opposite of a slut. Making them feel bad for not participating in promiscuous behaviors.
Example 1) Person 1: "He probably doesn't even have HPV. I bet he never watches porn, or has ever been to a strip club."
Person 2: "His girlfriend and him probably just talk on the phone about their feelings and shit. And I bet he's never asked for a nude; and they have never had phone sex. What a prig."
Person 3: "Stop prig shaming the poor guy!"
Example 2) Sister 1: "Aw crap Prude shaming is already in the Urban Dictionary!"
Sister 2: "Can you look up prude in a thesauraus?"
Sister 1: "Yes! Good idea! Crap I can't find any good words."
Sister 2: "Let's keep looking."
Sister 1: "How about Prig?"
Sister 2: "Fuck yeah"
Sister 1: "Prig Shaming has a good ring to it!"