1. (adj) ripped, buff, huge, or muscular
"Yo, check these guns; I fucking got jacked working in the quarry this summer."
2. (past tense) stolen
"Never park on MLK Blvd, unless you want your car to get jacked."
3. (past tense) hit, pounded, blasted, housed, or punched
"Don't fucking say that shit about MLK, unless you want to get jacked in the face -- bitch."
4. (past tense) to be completely freaked out by Jack Nicholson
"So I was watching the Shining for the first time, and when he burst through the door with that axe, I was completely Jacked!"