That '70s Show (that show about the '70s that was made in the '90s) was a sitcom smash, catapulting a handful of young actors into household name status. It featured Mila Kunis, Topher Grace, Ashton Kutcher, and a bunch more, along with memorable cameos from comedians like Cheech Marin and Mitch Hedberg, but it was Kurtwood Smith's perennially grumpy character, Red, that held the show together. His old school work ethic let the show wink at the changing values between generations, a message that had a particular resonance for the Gen Xers watching.
How exactly Red became such a stick in the mud was left a mystery for fans to solve. One Redditor posited the theory that Red is actually Richie from Happy Days, 20 years after going off to the Korean War. The theory goes that by the end of Happy Days, Fonzie and Richie are parted by the war, and without Fonzie to keep Richie cool and relaxed (along with the stresses of war), Richie comes back as Red, a complete square with no patience for shenanigans. The timeline even matches up, since Happy Days takes place twenty-odd years before That '70s Show. Plus, it would be satisfying to connect the two shows, since both are about looking back at a bygone era as a commentary on the modern day. As to what happened to The Fonz himself in this theory, we like to think of him riding the American freeways, fixing jukeboxes and dispensing life advice well into his old age.