Green’s Dictionary of Slang

1. (US) dating, ‘going steady’.

1914		R. Lardner You Know Me Al (1984) 104: This here Joe Hill the busher that Detroit has got that Violet is hooked up to was round the hotel.
1978		R. Caron Go-Boy! 140: The better looking and the more class a kid has the more likelihood that he will get hooked up with one of the tougher and more popular convicts.
2015		P. Doyle (con. 1969-1973) Big Whatever 20: Cathy was still hooked up with Johnny.

2. (US black) imprisoned.

1996		W.D. Myers Slam! 29: One day you would see a guy on the corner being slick and the next day you would hear he was hooked up in a cell somewhere.
2005		W.D. Myers Autobiog. of My Dead Brother 32: Iron City had so many brothers hooked up that it looked like Homeyville.