Awesome Moments: At the end of "Chicken A La Kotter", Kotter walks out after one too many nasty comments from his boss. He and the Sweathogs take their chicken and leave...but not before Arnold goes back in and puts the head of the chicken costume on the boss's head.
Horshack talking down the suicidal Mary Johnson. In return, she saves his life when he slips and nearly falls off the same ledge she tried to jump from.
Ear Worm: The show's iconic theme song, "Welcome Back" by former Lovin' Spoonful frontman John Sebastian, which topped the Billboard Hot 100 for one week in May 1976. In fact, the show was originally going to be named just Kotter until the producers heard the song. They loved it so much that they ended up renaming the show to incorporate the song's title.
Hollywood Pudgy: Judy Borden. The guys call her fat and make fun of her weight, but she's only a tiny bit thicker than the rest of the girls on the show.
Ho Yay: Though the guys were most definitely straight, they had their share of moments. Most notably Horshack constantly hugging Epstein and calling him "little Juan", or a season 4 episode where Vinnie asked Beau to "look at his body". Arnold and Vinnie also go way back to their toddler years, and Arnold sometimes acts as a Morality Pet to the normally clueless and self-centered Vinnie.
Horshack, especially early on. He puts up with a lot of crap from the other guys and has little to no self-esteem.
Beau, who reveals that he's had a tough life before coming to Bucchanan high school, never really knew the father he talks up so much and feels he has to con people into liking him just to make friends. He ends up playing a prank in order to impress the Sweathogs and keep them as friends, but even that backfires when Mr. Woodman refuses to believe it was him and blames the other guys.