O!wtd means Obesssed! with the disco, a term meaning 'obsessed with people knowing that they are a real fan of the theatrical rock band, Panic! at the disco.'
Though some of them are people who really are about the music, many of them pedal the speech that they are a real fan just because they liked them a year before they were released into the mainstream, and listen to more songs then just 'I Write Sins Not Tragedies'.
Ashley: OMG! You are so fake! You liked panic at the disco after they went mainstream and only listen to the singles!
Katie: Ashley is going crazy.
Hannah: no, its just that she's getting all O!wtd on everyone.