Photo: WENN.com

Billie Joe Armstrong of Green Day has revealed that his stint as a mentor on The Voice US has become embarrassing with contestants not knowing who he is.

The punk rock frontman, currently in the UK to perform a secret gig at Reading festival as well as promoting new album 'Uno!', spoke to The Sun about his experience of making reality TV and just why he chose to appear on the show.

“It’s always been a guilty pleasure for me and my wife Adrienne. And I’ve been friends with Adam Levine since he was 16," he explained.
 
Adding: “I was asked if I wanted to be a mentor and I had to choose between Adam and Christina Aguilera. I thought it would be more interesting if I was with Christina.
 
“But it’s hilarious as in some of the pre-recordings we’ve done with the younger kids. I’d be introduced as the surprise guest and they ask ‘Who the f*** are you?’
 
“Then Christina would say ‘Here is Billie Joe from Green Day’ and they are like ‘What’s a Green Day?’ It’s such fun.”

Green Day marked their time in London with a tiny gig at Shepherds Bush Empire. Of course, Gigwise was down the front and you can read our review here.

Photos: Green Day live at Shepherds Bush Empire