FURVERT!

4:3 animated animated_gif anonymous_artist anthro balls balls_inflation bodily_fluids canid canine cum cumshot ejaculation erection expansion genital_expansion genital_fluids genitals humanoid_genitalia humanoid_penis long_playtime male mammal medical object_in_urethra penetration penis probe restrained restraints scientific_experiment solo spread_legs spreading urethra urethral urethral_bulge urethral_penetration