Verb
fall off the back of a truck (third-person singular simple present falls off the back of a truck, present participle falling off the back of a truck, simple past fell off the back of a truck, past participle fallen off the back of a truck)
(idiomatic, Australia, US, euphemistic) Of an item of merchandise, to come into a person's possession through illegal or otherwise dubious means.
The movie is still in theaters, but I got a copy that fell off the back of a truck.