Surreal stages, events, or gameplay that somehow just don't fit have always been present, and even expected. Their crazy graphics, weird aesthetics and ideas make sure that we have absolutely no idea what's going on. But they have their charm, they are funny, or they're simply part of the experience—and so we love them.
We collected a bunch of them below.
Bad News in DmC
source: DmC Chapter 10
The Cardbridge In Alice: Madness Returns
source: Alice Wiki
The Nightmare Scenes In Max Payne
source: Max Payne's first nightmare
LSD Dream Emulator
source: LSD Dream Emulator Wiki
Inside The Red Dragon In Rayman Origins
source: Rayman Origins Dragon Trailer
Yume Nikki
source: Yume Nikki Wiki
The Space Harrier Stages In Bayonetta
source: Bayonetta Chapter 14
The Final Stage In Beautiful Katamari
source: superadamsworld's LP
Goro Majima's Karaoke Minigame In Yakuza: Dead Souls
source: Yakuza: Dead Souls - Goro Majima Karaoke
Stage 7 In Parodius
source: cubex55's LP
There are probably a lot more mind-cracking levels or games, so you should submit your own picks below (with visual support)!
DISCUSSION
Wow, any number of levels from Psychonauts could have fit here, but I can't believe that you forgot about The Milkman Conspiracy!!