The Black Eyed Peas star was left embarrassed when staff at United Airlines asked him to leave the first class lounge while he waited for a flight on Saturday because they believed he was trying to con them with a fake card.The Voice coach writes on Twitter: "#unitedAIRLINES is the worse. Im (sic) a member & I have my card to prove it. but they tell me my card is fake & kick me out the lounge #ouch... Ha ha ha I got kick out the club... #unitedCLUBsucks."It is not known which airport the star was waiting at when the incident occurred.