Combination of "fap", meaning to masturbate, and "apocalypse".
When so many people are simultaneously masturbating that it brings about the apocalypse.
God is supposedly omnipresent, which means he sees all, all the time. Fapture occurs when there are so many people simultaneously masturbating that God can no longer stand to see it all and comes back to tell everyone to knock it the hell off.
Did you see Jessica last night? She's so hot I swear she'll cause the fapocalypse.
Just like the apocalypse, you think your life is going to end if you have to eat all the food that is being served to you during a party. It is not uncommon that the leftovers of a foodpocalypse could save a third world country from starvation.
Oh my god, I went to a foodpocalypse last night. Our leftovers just saved Darfour from starvation.