A plane had to be diverted in the US after two passengers started fighting about a gadget that stops seats reclining.
A man travelling on the flight from New Jersey to Colorado had used a “knee defender” to preserve his precious leg room by preventing the woman in front pushing her seat back.
The gadget, which can be bought online for less than £13 ($21.95), has been banned by several airlines because of the arguments it causes.
But a passenger on United Airlines flight 1462 on Sunday was either unaware of the rule or simply determined to preserve that little bit of space.
Without telling the woman in front, he clipped the gadget onto the arms of his folding table so her seat was locked in place and he could continue using his laptop.
After trying unsuccessfully to move and finding out what was causing the problem, the woman complained to a flight attendant, who asked the man to remove the device.
When he refused, the female passenger stood up, turned around and threw a glass of water over him, according to officials.
As the pair continued their heated argument, the pilot decided it was best to divert to Chicago and leave the brawling passengers there.
They were not allowed to continue on the remaining journey to Denver, where the plane eventually arrived one hour and 38 minutes late.
Both passengers had paid to sit in the Economy Plus section, which already has four more inches of leg room than the rest of the section.
Chicago Police officers spoke to the passengers —both 48 — but made no arrests, deeming it a “customer service issue”.
The US Federal Aviation Administration can impose a civil fine of up to $25,000 (£15,000) for passengers who are unruly.
The Knee Defender was invented by Ira Goldman from Washington, who at 6ft 4in had become fed up with being “bashed in the knees over and over again” and wanted to help other plane travellers.
He told USA Today the packaging urges people to "be courteous" and listen to the flight crew. "Apparently that is not what happened here," he added.
Additional reporting by AP