Welcome Back, Kotter - Season 4 - Eps 17: Come Back, Little Arnold
To get up his nerve with Mary, Carvelli offers Arnold liquor. He doesn't like the idea at first, but as time goes on, he becomes addicted to drinking; developing a scary and unlikable new personality that only turns Mary away.
About Welcome Back, Kotter

Title: Welcome Back, Kotter
First Air Date: 1975-09-09
Last Air Date: 1979-06-08
Status: Ended
Rating: 7.2/10 (from 50 votes)
Language: EN
Seasons: 5
Total Episodes: 95
Network: ABC
Genres: Comedy, Family
Production Companies: Wolper Productions
Synopsis
Welcome Back, Kotter is an American television sitcom starring Gabe Kaplan and featuring a young John Travolta. Videotaped in front of a live studio audience, it originally aired on the ABC network from September 9, 1975, to June 8, 1979.
Cast

Gabe Kaplan
Gabe Kotter

John Travolta
Vinnie Barbarino

John Sylvester White
Michael Woodman

Ron Palillo
Arnold Horshack

Robert Hegyes
Juan Epstein

Lawrence Hilton-Jacobs
Freddie Washington

Marcia Strassman
Julie Kotter

Stephen Shortridge
Beau Shortridge