rule 34 anal anal sex anthro anus balls bound brown eyebrows cabinet crouching detailed detailed background eyebrows felid fur gag gagged genitals green eyes hands behind back humanoid genitalia humanoid penis laboratory equipment looking at viewer machine male mammal muscular muscular male muzzle object narrowed eyes navel nipples pantherine penetration penis presenting raccoon21 scientific instrument solo submissive submissive male tiger worried 3686075