Better living through robotics.

Does the world really need a robotic butt? Maybe not, but, in 2012 Japanese engineer Nobuhiro Takahashi and his colleagues at the University of Electro-Communications in Chofu decided to build one anyway. What did he call his incredibly odd invention? SHIRI, which is a fairly crude Japanese slang term for “buttocks.”

Takahashi’s animatronic bum-bum consists of a waist, thighs, and a pair of alarmingly authentic-looking butt cheeks. SHIRI definitely resembles the real deal but underneath its outer layer of silicon skin and foam, there’s a complex series of wires and a metallic skeleton.

SHIRI (not to be confused with SIRI, who’s just a robotic voice, not a robotic body) might make an excellent training tool for, on one end, proctology students or, on the other, unethical massage therapists. But instead of all that, Takahashi says he was most interested in studying how the butt reacts to stimuli, emotionally speaking. His team added a “gluteus maximus actuator,” which are robotic muscles that inflate or deflate

SHIRI in order to convey its mood. When the butt is in a good mood, it happily pulsates. When it’s frightened, it twitches like a frightened squirrel. These moods are activated by the actions of the user, which SHIRI tracks via a microphone embedded in its skin. The butt can “feel” slaps, pokes, strokes, and touches.

Read about more bizarre robots in Uncle John’s Robotica.