It means your hip, cool, with it, you know all the right people, you take all the right pills, you throw outrageous parties, you pay heavenly bills. There are lines on your mirror, (eventually) lines on your face, you pretend not to notice, you're so caught up in the race. Ref: Fast Lane by the Eagles
It means to be eccentric because you crave attention. Like you don't wanna look "scene" when you're 40 do you? It's just a phase for 12-14 year olds trying to figure out who they are in my opinion lol.