What happens when you put a huge cock and a tiny asshole together and shake it up a whole bunch? Prolapsicus maximus, that's what. I never finished med school but it's my professional suggestion that she pick up a pack of band-aids on the way home.
Cocks like this ought to be illegal, punishable by castration. Anything above 13 inches has got to go. They'll poke your eye out, prolapse your ass and leave with you a cocktail of STD's.