Why do Muslim jihadists assume that the 40 virgins they get are going to be hot young babes?

Hey, it's 72 virgins! And it's not from the Qur'an, but from the Hadith which is the second most important book in Islamic ideology. Regardless, it gets tricky. The Qur'an prohibits suicide or even murder, however, if you die as a Muslim, in the name of Allah, you become a Martyr and go straight to heaven. This has been taken out of context to signify that suicide bombers that do it in the name of Allah will go straight to heaven, all their sins forgiven.