1 : a theory that ultimate reality lies within a realm subcribing to the commonplace, ordinary or bitchin. If five others are doing it, it must be hot!
2 : the practice of forming your ideals or living under the influence of what other people are doing, or consider cool at any given moment.
3 : literary or artistic theory or practice that affirms the preeminent value of whatever is popular with the general public at a specific time and place, regardless of how silly a given trend may be, or how short it may last, and how foolish you will feel when it's over. At least you weren't alone right?
Bob: "You got one? Me too! Hey thats a metooism ain't it?"
Joe: "Yep it's a meetooism alright, hey check out this new tongue piercing I got Bob."
Bob: "WTF? Another metooism? I got one too dammit!"
Joe: " Yeah it doesn't help that we both have goatess too, this metooism lifestyle is rather craptacular isn't it? I think I'll try something different, and go shave my head."