When you've pulled out all the stops to ensure that you will get laid and you get all the way to the bedroom only to have your advances rejected at the last moment due to some allegiance to an invisible deity or code of ethics from an outdated book.
John: Dude, I had it all set up, house to ourselves, candles, a stupid chick movie, I played tears in heaven for her, i had my face as smooth as a baby's ass, got her wet, took her to the bedroom, got naked, and she's all like, "the bible says.. blah blah blah." I was like omfg!
Dave: You totally got Godblocked dude. Did you enjoy blue balls?
John: Eat shit asshole.