That's right, Black Eyed Peas singer Fergie may be a fitness fiend, but she was recently barred from boarding a flight after being branded unfit to travel.

The reason? She was plastered! We're talking Katie Rees style (minus the hooking up with other girls part)!

The singer, real name Stacy Ferguson, was due to fly from Los Angeles to the UK with bandmates Will.I.AM, Apl.DE.AP and Taboo, but was not allowed to board the plane because of her drunken state.

One can only wonder if this has ever happened to Mischa Barton. One can only assume it has. An onlooker tells Britain's Daily Mirror:

"Fergie was falling all over the place and had to be supported. She was in no state to fly.

Apparently Josh Duhamel's squeeze didn't exactly take the news well.

"When she was prevented from boarding she couldn't believe it. She was drunkenly ranting at staff but could barely string a sentence together. It was very embarrassing."

Fergie Ferg delayed the flight for an hour while her luggage was removed, but her three band mates remained on board the plane bound for London.

Yikes. We would expect Britney Spears to be on every no-fly list there is, but the Duchess? A spokesperson for airline Virgin Atlantic says:

"We can confirm a female passenger was denied from boarding as she appeared intoxicated and was therefore unsuitable for travel."

Her band mates, sick of her drunkenness, reportedly left her butt at the airport. But that's one fine butt, that's for damn sure.