Taking to his Instagram account, Armstrong posted a picture of K-pop star Psy, and what he had to say about the "Gangnam Style" hit-maker was far from congratulatory.

"This dude is the herpes of music," Armstong wrote. "Once you think it's gone, it comes back." The Green Day singer also added a series of hashtags: #herpes, #flarup and #pleasegoaway.