The Thing in The Thing killed everyone except Kurt Russell (and another guy but I don't know his name). A few days later a rescue team shows up and finds Kurt alive, because he survived by eating the Other Guy. But Kurt doesn't tell them that he became a cannibal. He tells them about The Thing, and how it killed everyone. The rescue team just thinks he's crazy, and he gets sent to an asylum for the criminally insane. Over the next few months, Kurt is put through electro-shock therapy and eventually forced to believe that the events of the The Thing all happened in his mind and there's no such thing as Things. He breaks down and starts crying in the middle of a group therapy session and all the other crazy people group hug him. Then the camera pans up, and up, and fucking UP into space for ten minutes until it stops at a distant alien planet. This is Planet Thing, home of The Things. And right in the middle of the planet is a giant statue of Kurt Russell.
One year later, back on Earth, Kurt Russell is released from the Crazy House. Some kid rides past him on a tricycle, then stops for a second and yells "Hey, fuck you, Krazy Kurt!" then rides away. Kurt yells "No, fuck YOU", but he waited too long before saying it so the kid was too far away to hear him. Also he says it right when a gang of teenage street-punks are walking past, so they thing (I mean think) Kurt was talking to them. The Punk Leader is like "What'd you just say, old man?" and he pulls out a switchblade. Kurt's like "No, I wasn't talking to you" but these rapscallions don't believe him. They start pushing him around, and Kurt's like "Don't make me angry, you wouldn't like me when I'm angry" but they keep pushing him, which makes him angry. So Kurt is forced to kick all their asses. Then he steals a skateboard that one of them was carrying and skates away.
Now there's a montage of Kurt Russell building something. We can't tell what he's building yet, but whatever it is, it's big. The street punks show up and they're like "Hey old man!" and Kurt turns around, thinking they're back for round two, because it looks like Punk #1 is reaching for his switchblade again. But they're just like "Looks like you could use some help" and Punk#1 pulls out a hammer instead of a switchblade. They help him build, because now they respect him. One week later, they've finished building and one punk is like "So what is this, old man?" And we finally see that they have built a space ship. It looks exactly like the one from The Thing, because Kurt was just putting on an act the whole time he was in the asylum. He was just waiting to get out so he could travel to Planet Thing and get revenge on the Things that killed his buddies. He gets into the ship and flies away.
One light year later, the USS Krazy Kurt makes a crash landing. Kurt steps out and says "Finally, here I am on Planet Thing." But we saw Planet Thing earlier so we know he isn't really there. There's a sign right next to him that says "Welcome to Loch Ness", Kurt reads it and is like "What a strange language these aliens have." Then he starts killing everyone he sees, because he thinks that they're Things. In what is later known as the Kurt Russell Massacre, he brutally murders over 300 people before a police sniper takes him down with a bullet to the chest. Kurt is almost dead, but he is still able to crawl back into his space ship and start the self-destruct sequence. He pulls out a bottle of whiskey that he had been saving for this special occasion, and looks at a photo of him and his friends who were killed by The Thing in The Thing. "I did it..." he says, a single tear rolling down his cheek. "I saved the world."