Mainly UK, especially south-east England. (v) To use information (true or fictional) to provoke, tease or deceive. (v) To invent with the intent of conning. (n)A deceptive or provocative act. A "Wind-up merchant" is somebody who is disposed to wind others up, a habitual liar, or prankster. Origin: from the act of winding a clock or other clockwork device.
"He claimed he had been in the SAS, but it was just a wind-up." "Bob would wind Mike up by claiming he'd slept with Mike's girlfriend" "That blokes a wind-up merchant" "It seemed at first glance to be two mathematicians arguing number theory, but it was a wind-up - they were just talking nonsense, it turned out."
to tease, usually with some malice
He said he's meet her at 7 o'clock, but after she'd been standing in the rain for an hour she realised it was a wind-up