What makes Eric Cartman such a unique character is that this Grade 4 student is quite literally capable of anything. And on a show like South Park where virtually nothing is outside the realm of possibility, that's saying a lot. Being patient is certainly not one of Cartman's characteristics, though, which led him to do some unintentional time travel and become South Park's version of Buck Rogers.
Calling Cartman impatient is a massive understatement. Whatever it is that the boy wants, he wants it now. Unfortunately for Liane Cartman, she is often the person to take the brunt of Eric's whining when it comes to not being able to wait for anything.
This cost him big time in Season 10, Episode 12. The Nintendo Wii was three weeks from coming out and, to the shock of no one, Cartman could not wait any longer. Honestly, this was true of a lot of people at the time, as many gamers were excited for that console when it dropped. But Cartman took things to a new level when he froze himself in the mountain snow to wait for the Wii.
To pull this off, Cartman needed help. Most of his friends would have tried to talk him out of it, so he brought Butters in. While he was willing, Cartman should have expected Butters to mess up. His job was to retrieve him when the Wii arrived, but an avalanche buried Cartman. Butters couldn't find him, and Cartman ended up frozen until he was revived in the year 2546. That's when Cartman became Buck Rogers.
Trapped in the future, Cartman got involved in some really weird wars between different Atheist factions. This included one entirely made up of super-intelligent sea otters. He spent two episodes in this future, finally returning to his correct timeline at the end of Season 10, Episode 13. Unfortunately for Eric, he returned two months before the Wii launch, meaning he had to wait even longer than he would have if he had not frozen himself.
But there's another side to this story, one that calls his journey into question. Cartman is an unreliable narrator. So it's entirely possible that none of this happened. In Season 13, Episode 5, Cartman tries to take credit for a joke that Jimmy made. Kyle explains to Cartman that his mind unconsciously develops an intricate web of lies that even he isn't aware of to support his overblown ego.
Another example of this is Cupid Cartman. He's a small version of Cartman who looks a lot like Cupid that only he can see. When he appears, Cupid Cartman seems to be real and a figment of the young boy's imagination at the same time. The problem is that the line between fact and fiction is incredibly blurry, to say the least. Ultimately, South Park's viewers can never be sure if anything that happens from Cartman's perspective can be trusted.
When Cartman is the narrator, there is always a very real chance that nothing is true. Given South Park's nature, Cartman could have ended up as a Buck Rogers-like hero in the future. At the same time, it's equally likely that Cartman made the whole story up and lied to the audience as part of his mental gymnastics to avoid waiting.