Green Day frontman Billie Joe Armstrong has hit out at 'Gangam Style' singer Psy, calling the South Korean popstar "the herpes of music." Armstrong made the comments via his Instagram account this afternoon (May 8), posting a picture of Psy alongside the caption: "This dude is the herpes of music. Once you think it's gone, it comes back. #herpes #flareup #pleasegoaway". Armstrong is a frequent user of Instagram but has rarely used it to pass comment on other musicians, preferring instead to share pictures of his bandmates and on the road updates. Last month, Psy put out his new single 'Gentleman', the follow up to his YouTube hit 'Gangnam Style'. The video for the track has been banned by a broadcaster in his native South Korea, who blacklisted the singer for kicking a cone that says "no parking", explaining that the scene didn't meet its standards.NME