Characters from The Simpsons just unexpectedly showed up within the pages of Marvel Comics. In a surprise cameo in Immortal Hulk #32, a group of kids being interviewed about the new Hulk, Xemnu, are clearly based on Bart, Lisa, Milhouse, and Nelson.
The Simpsons have made references to Marvel Comics and characters in multiple episodes since it first debuted more than 30 years ago, including Homer Simpson turning green and angry just like the Hulk. With Disney now owning Marvel Studios and Fox, The Simpsons recently had a more ambitious crossover that featured Marvel Studios president Kevin Feige voicing a parody of Thanos called Chinnos. The latest cameo in the comics is much more subtle and easy to miss, however.
In the latest issue of Al Ewing and Joe Bennett's superb Immortal Hulk, the Living Hulk Xemnu continues his manipulation of the general public to believe that he's a lovable star of the children's show Magic Planet and the best Hulk there is while painting the actual Hulk as a dangerous monster. His tactics appear to be working as Immortal Hulk #32 opens with people being interview about just how great Xemnu is. In one of the shots, a group of four kids is shown praising Xemnu. "I actually saw him, uh - aw man, what's he call it - embiggen. I saw him embiggen. Xemnu's the best," the kid in the front says. Take a closer look and you'll notice those characters are styled exactly like some of The Simpsons most iconic characters.
From left to right we can see a kid with a similar appearance to Nelson Muntz, Bart Simpson, Milhouse Van Houten and in the very back right, Lisa Simpson. If you think that it's purely just a coincidence, there are even more hints in the panel. Look at the name of the school - while it's intentionally blocked out my speech bubbles, it sure seems to spell out Springfield - the home of The Simpsons. Furthermore, the phrase embiggen was popularized (and defined in its current form) in The Simpsons episode 'Lisa The Iconoclast." It's used multiple times (along with the word cromulent) throughout the episode and is even featured in Springfield's town motto "A noble spirit embiggens the smallest man."
The panel is about as close as you can get to doing a cameo from The Simpsons, without officially doing a cameo from The Simpsons. There's no way this was a coincidence. It's so well done. So there you have it, The Simpsons exist in the Marvel Universe.