The Black Eyed Peas star tweeted:"#unitedAIRLINES is the worse. Im a member & I have my card to prove it. but they tell me my card is fake & kick me out the lounge #ouch (sic)," he said in a post.
"I fly so much... a business should know who their customers are," he wrote.
The musician then revealed that he was recognised by the pilot.
"I get kicked out of the @united lounge because they say I'm not a member ... oh well ... and then the @united pilot asks me to take a selfie."