Everybody loves easter eggs, especially when someone figures them out themselves. I personally get a lot of enjoyment out of finding Easter Eggs in things like superhero movies or video games where there are a ton of them. But now that Ben 10 has been running so long, the writers have dropped in lots of easter eggs about either the past episodes, the creators of Ben 10, or other things. Here's some Examples: Rex's "theme song" in Hero's United is to the tune of the original Ben 10 theme and Magister Palliday mentioned Xylene from that one episode in the OS in "Gone Fishin."
Here's my favorite Easter Egg!
Episode: Ken 10 (Original Series)
Kenny's alien friends gathered for his birthday and you will notice one of them wears the same clothes as Billy from the Grim Adventures of Billy and Mandy. He's also got a big nose like Billy. He's also voiced by Richard Steven Horvitz like Billy! I thought this was really neat because it was the first time Ben 10 reached out to the other Cartoon Network Shows.
What's your favorite Easter Egg?