Most of us have been there – returning from the supermarket or mall to find a dent in the car from someone else's trolley.
New data shows just how much of a problem rogue trolleys are, and why now's the time to watch out for them.
Data collected between 2010 and this year show runaway trolleys are a big problem.
"In the last five years, we have received around 1000 car claims in relation to the damage caused by those shopping trolleys," says IAG spokesperson Shelley Huang.
That's 200 claims every year. With all the Christmas goodies, a full trolley can weigh 50kg, doing more damage on impact.
"Our average cost for this year was $1100," says Ms Huang.
If your car's more expensive, repair work can easily reach $15,000, and those figures don't include what's not reported.
"If it's under $300 you probably wouldn't bother, but if it's over your excess fee most of them would like to make a claim," says Ms Huang.
Now's the time to watch out. The three months over Christmas and New Year is when you're most likely to encounter a rogue shopping trolley.
"We always experience a high number of claims over Christmas, so this Christmas I don't think it will be any different."
The best advice is to park where it's quiet if possible, and well away from trolley parks.
Panel beaters are the only people who benefit from runaway shopping trolleys.