The actor couldn't be bothered getting up early and trekking to the set - to play Hugh Grant's slovenly flatmate, so be bought a tent and a sleeping bag and slept at a campsite minutes from the film mecca.
He tells Playboy magazine, ""We were filming at Shepperton, a studio that can take several nightmarish hours to get to and from. I thought, 'How am I going to get around this torturous journey?'
""So I got a tent and a sleeping bag and camped near the studio, which sort of helped the whole unkemptness of the character.""
And Ifans famously didn't shower or brush his teeth during filming - so he'd really become the unhygienic character he was playing opposite Grant and Julia Roberts.
He adds, ""Julia never saw me as I normally look so she probably thought I was some guy they found in the street.""
But he still arrived in style for work every day.
The Welshman explains, ""Due to insurance and liability issues, a limo still had to show up to drive me to the studio. So every day this guy who owned the campsite would watch me walk across the field, get into a limo and be driven away.""