The Irish boyband - who are known for their clean-cut image - have admitted they can get away with "leading double lives" because no-one is aware they have such a rebellious streak.
Kian Egan explained: "We can put the drink away, b****y sure we can. Come on, we're Irishmen! We've been at parties where we've got away with murder because everyone assumes we're boring. The paparazzi never hang around for us, so we can almost lead a double life.
"Mark and I are probably the worst. We've done 40 nights on the trot before and I guess some people would be called alcoholics for that."
However, despite the band's boozy nights out, Kian confessed the group - completed by Nicky Byrne, Mark Feehily and Shane Filan - have a strict anti-drugs policy.
He added to Fabulous magazine: "We've never gone down that road. I've never been offered hard drugs and if we've been at parties where it's going on we've left immediately. I don't want to be around it.
"And anyone who works with us knows that if there's even a whiff of drugs they'll be sacked."