The Chicago Tribune said the unnamed man was kicked off a Spirit Airlines flight, bound for Orlando, Fla., at O'Hare International Airport.
The report said the man and the woman with whom he was traveling Sunday morning became "verbally abusive" and threatened physical harm to flight attendants. His pants were "excessively low," hanging below his buttocks, Spirit spokeswoman Misty Pinson said.
The couple gathered their things and left when law enforcement arrived, but they were booked on the next Spirit flight to Orlando. The original flight was delayed about five minutes, the Tribune said.
The airline's code requires customers to wear shoes and "adequate" clothing, Pinson said.