Fell off the back of a truck is an idiom which refers to something stolen, something obtained illegally and often sold at a large discount. Related terms are fall off the back of a truck and falls off the back of a truck. Fell off the back of a truck is an American English and Australian English term. The corresponding British English terms are fell off the back of a lorry, fall off the back of a lorry, falls off the back of a lorry, though fell off the back of a truck is also sometimes used in Britain. Originally, the term referred to something shoddy, it now refers to any illegally obtained item. Fell off the back of a truck is first found in America in the early twentieth century. Interestingly, one often finds the term literally fell the back of a truck in news stories to signify that the report is not referring to a stolen item or stolen items.
Who among us hasn’t bought, or know someone who’s bought – something that mysteriously fell off the back of a truck. (The Toronto Star)
Stereo equipment that “fell off the back of a truck.” (Esquire Magazine)
“If you happen to be at your local watering hole and someone sidles up to you with a, ‘Psst – do you want to buy a cheap coffin, fell off the back of a truck,’ give Crime Stoppers a call,” he said. (The Guardian)
To some it matters not at all and they are willing to buy anything that fell off the back of a truck. (The News Tribune)
“We will be getting the strengths of the region to full potential, rather than waiting for what falls off the back of a truck out of Brisbane.” (The Courier Mail)
It literally fell off the back of a truck, according to Timaru Herald deputy editor Grant Shimmin, seen here assuming modelling duties. (The Timaru Herald)