To Steal or Jack a car that is not yours.
The stolen cars are usually muscle cars, import and domestic street cars, donks and cars of luxury or high trade in value. This practice is very common in cities with many "Chop Shops" such as: Oakland, Detroit, St. Louis, Los Angeles and Las Vegas.
The phrase was made known by the movie "Fast and the Furious" (2001) when Dominic (Vin Diesel) finds out Brian (Paul Walker) was incarcerated for "Boosting Cars".
Dom: Boost cars?
Brian: No, never.
Dom: Do time?
Brian: Couple of overnighters. No big deal.
Dom: What about those two years you did in juvie for boosting cars? Tucson, right? I had Jesse run a little background check on you, Mr. Brian Earl Spilner.