Originally Posted by tore

Although I can't say with 100% certainty that the story is against masturbation, there is the story of Onan in the bible. God wants him to impregnate his dead brother's wife, but Onan pulls out and spills his semen on the ground each time instead. Or something along those lines.

God is angered and kills him. Many have interpreted that story as saying that spilling your seed, masturbation, is a sin. The word masturbation is "onani" in norwegian, after Onan.

However, girls don't spill their seeds by masturbation anyways.