Well, cross that last one off the list. Starlee Kine's delightful podcast Mystery Show solves arcane if minor mysteries. In the sixth episode, "Kotter," Kine digs into a depiction of the Sweathogs on the side of a 1977 Kotter lunch pail, which was spotted in the Smithsonian. Sure, it's not exactly Perry Mason, but it's fun. 

In the painting, Epstein and Barbarino appear to be fighting. Dangles his jean jacket accusingly in front of Barbarino. The sleeves of the jacket have been tied in knots. This is not a scenario from the sitcom. What gives?

The podcast watches all the episodes, tracks down the artist behind the lunch box, series co-creator Alan Sacks, and chats with Gabe Kaplan over the phone. Listen to it below.

Along the way, we hear anecdotes about Phil Spector, licensing rights, and wrestling. In the end, we learn the scene was based on a common cowboy prank. Probably.