They ran out of virgins.

Actually, the 72 virgins are here in heaven because assholes like you murdered them before they could experience the pleasure of sex. So youre here to service them. Since theyre virgins, theyre quite sexually ravenous; and, frankly, youll be on constant, exhausting duty. The bomber responded, Well, I guess I can live with that. How hard can it be to keep 72 women satisfied for all eternity? And Allah replied, Who said they were women?