Opposite of a hipster. As in a person that loves everything that's popular and prides herself/himself in that devotion to popular culture.
Fuck that popster and his Justin Bieber shirt!
Sadly these days almost everybody is a popster. Popsters being those people who for some incomprehensible reason like to dress in glittery glamour clothes and listen to pop music designed for the sole purpose of making as much money out of tasteless listeners as possible by over advertising and portraying ideals which can turn people into rather selfish wannabe stars.
Person 1: "Oh my God! did you know Taylor swifts new album is coming out in 4 days, 4 hours, and 44 minutes?!"
Person 2: "Did you just ask me why I find popsters annoying?"