Happy Days S10 E05 Little Case of Revenge

"Those were the days of the 1950's...filled with innocence and the promise of even better days to come."

Fonzie receives a good citizenship award from the Milwaukee Chamber of Commerce, but the ceremony is interrupted by a disgruntled childhood classmate of the Fonz who's been waiting 17 years for his revenge. They agree to settle their differences, but Ashley asks Fonzie to promise not to fight.