The group are currently working on a follow-up to their 2004 disc, American Idiot, but the stark similarities in vocals between Green Day front man Billie Joe Armstrong and those on the Foxboro Hot Tubs' EP have got Internet blogs wondering whether the Holiday hitmakers have gone undercover to experiment with a new 1960s-inspired sound. [listen at http://www.myspace.com/foxborohottubs]

If Green Day are proven to be behind the Foxboro Hot Tubs, it would not be the first time they have released tracks under a pseudonym [Doesn't just about every emo/pop-punk singer these days try sound a bit like Billie Joe? The trick we hear is to hold your nostrils closed while singing. More on the past secret release here] - more on this story