everyone will have sex on this day (12-21-12) because the end of the world is supposed to happen. then the next day everyone will be like "well i guess i'm still alive so the world isn't going to end" so they just fuck again for the hell of it.
alyssa and cole had 2012 sex on the supposed last day of the world, but when it didn't end they banged some more.
It is when a female vagina is blocked off due to extra tissue and a cock can not get in during sexual intercourse.
My friend's ex was a blockcock and didn't tell him about it.