A subculture based on conscious, artificial adoption of things that are in widespread use, proven to be acceptable, or otherwise inoffensive. Ultra-conformists.
First featured as a fictional population in the webcomic Templar, Arizona, but normcores are totally real.
Oh, shee-it! You just got gang signed by the worst of 'em! Y'see the slight forward tilt of the chin, and the causal "hey" with the silent H? That means he's NORMCORE. Dangerously regular. Dresses only in T-shirts and jeans, uses slang appropriated from other subcultures, but only 3 years after its first use, an' only after it's been used in a sitcom."