FURVERT!

2014 accidental_transformation animal_genitalia animal_penis anus asinus backsack balls big_balls big_butt big_penis butt comic donkey equid equine equine_genitalia equine_penis erection fasttrack37d genitals growth hi_res hooves human long_penis male mammal nude penis perineum slightly_chubby solo tail thick_penis transformation transformation_sequence vein veiny_penis