fall off the back of a lorry

Of goods or merchandise, to be acquired by illegal or dubious means; to come into (someone's) possession without being paid for. Primarily heard in UK. Danny says he has several laptops and smartphones he wants to sell for cheap—sounds like they fell off the back of a lorry to me. A: "Jake's been peddling a bunch of flat screens for a great price." A: "They probably fell off the back of a lorry then. I wouldn't go for them, if I were you." These prices seem a little too good to be true. You sure this stuff didn't fall off the back of a lorry?

fall off the back of a lorry

BRITISH, INFORMAL

If you say that goods have fallen off the back of a lorry, you mean that they are stolen goods. We bought some really excellent wine from a woman who clearly caught the bottles as they fell off the back of a lorry. Note: You can also say that you got or bought something off the back of a lorry. Pete once bought the boys a bicycle cheap off the back of a lorry.