The Werewolf Transformation
The Big Bang Theory Season 5 Episode 18 (02/23/12)
The episode opened with Sheldon going to get his hair cut only to find out his barber is in the hospital. Sheldon attempted to let the barber’s nephew cut his hair, but couldn’t do it last moment.
As Sheldon went days past his haircut he became increasingly more lackadaisical about things he normally cared about. Penny and Leonard convinced him to embrace the change to see where it led.
Meanwhile Howard reported for astronaut training, while video chatting with Bernadette every night, she could see he was not going to make it through training and showed up to help him only to find his mother had gotten there first.
After a week without a haircut Sheldon woke Penny and Leonard at 3am playing the bongos, and left them standing in the living room saying he was going where ever the music took him, which was to Amy’s place.
At Amy’s Penny convinced Sheldon to come home and let her cut his hair so things could be back to normal.