Rule 34 Dev - 2boys ass ass_shake blue_eyes blue_sky briefs brothers cstdraws fence ferb_fletcher grass gray_briefs gray_underwear green_hair highres light_skin male monotreme multiple_boys music_player musical_note open_mouth perry_the_platypus phineas_and_ferb phineas_flynn platypus red_hair shota siblings sky stepbrother stepsiblings tongue tongue_out underwear underwear_only|4021247719