The power of orgasm compels you!
Nothing like making a pair of highschool girl ghost pass on to the afterlife by showing them the power of onanism.
All jokes aside, the ending and implications of what happened did give me a bit of a scare; not because of what happened, but because of what COULD have happened: them seeing the close friend whom they had recently fought with (by virtue of insensitive comment) and with whom you were trying to reconcile dead by what appears to be suicide... never getting a chance to say goodbye or apologize, her being mad at you till her death by what appears to be your actions... yikes.