7x11 - Happy Days

Unknowingly, Richie, Potsie, and Ralph are invited to a party hosted by the She Devils gang in which the Devil who brings in the biggest nerd wins a $100 prize. After Richie discovers the purpose of the party, he and the guys head for the door. However, several Devils come in carrying a sack containing a guy who jilted the sister of the gang's leader. The guy is Chachi.