Remember Adventures of Sonic the Hedgehog? No? Well, even if you've never seen a single episode, you've certainly seen frames from one. Ever since the dawn of YouTube, this 1990s kids' cartoon has been memed to hell and back, something which has passed from generation to generation.
It looks like Sonic Team hasn't forgotten about this iconic part of the series' history either. As spotted in Sonic X Shadow Generations' Movie Pack DLC, there's a reference to Eggman's appearance in Adventures of Sonic the Hedgehog - which makes sense since he's the centre of most of the more well-known memes.
With the DLC out now, fans have had a good look at the new stage that it adds to the game. And while some are frustrated with how quickly you can breeze through it, there's certainly a lot of detail thrown in there to encourage you to take it slowly for a change.
One of them is, indeed, a reference to Eggman. Or, more specifically, Eggman as he appeared in Adventures of Sonic the Hedgehog. Or, as this is often shortened to: Pingas. That's a reference to a misheard line in the show, where it sounds like Eggman...