FURVERT!

2014 accidental_transformation animal_genitalia animal_penis anus asinus backsack balls balls_expansion big_butt butt butt_shot close-up clothed clothing comic crotch_shot donkey english_text equid equine equine_genitalia equine_penis erection expansion fasttrack37d fur genital_expansion genitals growth heartbeat hi_res human male mammal partially_clothed penis sheath solo species_transformation text torn_clothing transformation transformation_sequence transformative_clothing underwear vein veiny_penis writing_into_reality