I never heard anyone use the word in real life. I have an idea what it means...that you're being something that you're not. Example: wearing clothes that "skaters" wear, but you're really not a skater yourself. Am I on the right track?
Yeah thats the gist of it. Similarly, i think of a "poser" as a middle-class (typically white) kid who wore grungy or faux-vintage clothes and claimed they were all about the struggle because they couldnt afford books for next semester.
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Do you know people? Have you interacted with them? Because this is pretty standard no-brainer stuff. -33girl