Yume Nikki: Madotsuki's pink shirt with a chekerboard pattern in the center.
This was lumped together with the "examples that just seem to be cool outfits, not an outfit taking on a life of its own," and deleted. However, Madotsuki's shirt is iconic to that character: just as Superman wouldn't be so without his S-Shield, Madotsuki wouldn't be herself without her 3 x 2 checkerboard pattern. Otherwise, she would be inseparable from any other girl with brown hair and braids. Most fanart portray her as wearing the pink shirt and/or the checkerboard pattern, so it's certainly recognizable to those even remotely familiar with the charcter. While Yume Nikki is an obscure game, and thus hasn't penetrated into pop culture anywhere near the extent of other examples, Madotsuki's shirt is still unique enough to the character that it fits the definition of a Memetic Outfit.