Ben 10 season 3 episode 1 : Ben 10,000

When Ben and Gwen forget about Grandpa Max's birthday cake, the two kids wind up bickering over who's to blame. But when a mysterious stranger appears out of nowhere and kidnaps Gwen, Ben follows her into a strange portal as XLR8. When the dust settles, Ben suddenly realizes where he is: the future, in a world where humans and aliens live peacefully. Ben, however, is taken aback when he learns that Gwen's captor is actually her own future self, an accomplished magician to boot. Future Gwen reveals that the current Ben is now a world-renowned hero with 10,000 different alien forms. But, upon meeting his future self, Ben realizes that the future Ben is all business and just can't relax, not even for his own family.