rock rental n. an automobile loaned in exchange for crack cocaine. Editorial Note: This term has been especially common in New Orleans, Louisiana. The 1998 citation suggests a gun as the item loaned, but it is the only mention found of such a trade, and as it is a summary of a video transcript, it is not necessarily reliable. A synonym is crack ride or rent-a-rock. (source: Double-Tongued Dictionary)
Further reading
Unparalleled misalignments are pairs of phrases in which the words in one phrase are each synonyms of the words in the other, but the phrases themselves mean different things. For example, the phrase blanket statement can be paired with cover story...
Here’s an unparalleled misalignment in which the words in one pair are synonyms of the words in the other pair: organic chemistry and carbon dating. This is part of a complete episode.
Related
Years ago, I remember the term being ROCK-RENT.