A man threatened a member of staff with a gun at a local shop over a £1 discount on alcohol.
The incident was caught on CCTV and shows the customer brandishing a gun after he was refused a discount on a bottle of beer.
He walked into the newsagents and picked up two bottles, which he put on the counter. He asked the shop assistant for a discount, then aimed a gun at him.
Terrified, the assistant told him police were on the way - to which he replied "I don't want that".
He then paid £3 for one bottle and put the change in a charity box on the counter in the One Stop Store on Stretford, Greater Manchester.
The suspect was described as a white male with a heavy build, aged between 20 and 25. He was said to be 5ft 5in to 5ft 8in, with a shaved head and a large face. He was wearing a black baseball cap bearing a logo.
DC Andy Warren said: "This was, quite frankly, a bizarre robbery the likes of which I have never come across before.
"Quite what the offender was thinking I do not know but his actions were extremely strange.
"However, I want to be absolutely clear that while some might find his behaviour odd, this is no laughing matter.
"He pulled out a gun and cocked it in an intimidating manner in front of a shop worker who had no idea what he was going to do and whether he would genuinely fire the weapon."
The CCTV footage has been released in an attempt identify the suspect. Anyone with information should call police on 101 or the independent charity Crimestoppers, anonymously, on 0800 555 111.