I hope when you buy your Christmas presents, you won't buy anything that's fallen off the back of a lorry.
It might be a good price but it may well lead to problems - that's because the phrase means it's stolen.
Two of Britain's most popular villains are the Trotters. They will do anything to avoid work and usually buy and sell stolen and damaged goods.
Del Boy is the fast talking, clever con man but his brother Rodney, isn't so bright.
Here they are selling a car. One, careful owner only! Yeah sure.