One who only likes new or "young" music. If it hasn't come out within the last 6 months, it isn't good.
Ralph: Don't you just love "Heart-Shaped Box"?
Betty: I used to.
Ralph: Why don't you like it anymore?
Betty: It's just so 90's.
Ralph: Geez, what are you, a musiclester?
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi