Someone who attempts to join a social group or clique for reasons of popularity or recognition rather than because they believe in what the group represents.
Why is he even here? He can't even ollie! He's such a poser.
A derogatory word for someone a certain person does not particularly like. Used to show how much person a knows about the "scene" by insulting person "b".
Person B: Hey! Do you like Taking Back Sunday?
Person A: Oh my god. You are so lame. Taking Back Sunday isn't cool.
Person B: ...
Person A: And are those Converse? Don't you know everyone wears Vans? You're such a poser.
Person B: *slits wrists in the bathroom*