A tiny gun measuring just 44mm triggered big trouble for its owner when he found out the key ring is classed as a firearm.
Michael Lawrence only paid a few pounds for the item, marketed as the "smallest pistol in the world," and was more interested in its "beautiful presentation box", a court heard.
But the little weapon was capable of firing projectiles and doing serious harm.
Newcastle Crown Court heard police found the box set containing the pistol, mini flares and 2mm blank cartridges at Lawrence's home in Byker, Newcastle, in May 2019.
Jessica Slaughter, prosecuting, said: "It was test fired and found to be in good working order.
"It was deemed to be a firearm.
"The defendant said he didn't know it was a firearm."
Lawrence, 34, who has six previous convictions, pleaded guilty to possessing a firearm.
Judge Amanda Rippon told him: "You have to be more careful when you look at things which might, on the face of it, look like a toy or a novelty, but is not.
"Because of the force with which pellets could be fired, it could cause very serious harm if it hit someone's face, for example, even in jest while messing about."
The judge added: "I think you know you made a mistake and you won't do it again.
"I really hope you understand the court takes weapons very seriously. Given, however tiny this may be, it can cause serious injury to people, the courts generally send people to prison.
"The unique circumstances surrounding this offence lead me to take a wholly exceptional course.
"This was a tiny gun which did fire a projectile but you will not have realised it was a dangerous article.
"I accept you bought it to help a friend and were more interested in the rather beautiful presentation box it was purchased in."
Lawrence, of Dunn Terrace, Byker was sentenced to a six month community order with a rehabilitation requirement.
The court heard he has worked hard to turn his life around in recent years and the judge said the pre-sentence report was impressive.
Paul Caulfield, defending, said Lawrence has health problems, including anxiety and depression.
He added that it was bought as a key ring attachment.
