They wanted a simple garage sale advert, to help sell some unwanted baby clothes and knick-knacks.
But the young family ended up being pestered by "gun nuts", visited by undercover cops and terrorised by strange figures lurking outside their Burnside, Christchurch, home.
Bianca Jolley and her partner Tim Austin booked a free advertisement in the Buy Sell & Exchange newspaper for their garage sale last Saturday.
But they were shocked to discover a mistakenly printed headline, in red capital letters, above their classified ad which read: "RIFLES, SHOTGUNS AND HANDGUNS".
Their phone soon started ringing. Ms Jolley, 32, said: "These gun nuts kept phoning up asking what shotguns we had, and we were like, 'Excuse me?"'
But the printing error took a sinister twist when night fell.
"About 11pm, Tim and I went outside for a smoke and we could see people lurking in the shadows," the mum-of-two said. "They were there for about an hour, before we let the dog off [a large bull mastiff] and they ran off.
"It was very scary, especially with the kids sleeping inside."
On Saturday, the day of the sale, gun enthusiasts turned up all morning. And the couple are certain that at least one "plain-clothed police officer" came snooping through their sale to check whether they had any guns.
"We've never owned a gun, or even a gun licence," Ms Jolley said.
Mainland Press Ltd, which publishes the Buy Sell & Exchange, has apologised to the family and offered them some free cinema passes. But the couple are still fuming. Mr Austin said: "I'm not happy at all. It's a pretty big mistake to make, saying we've got guns in a garage sale advert which publishes our address."