Green’s Dictionary of Slang

1. accustoming oneself to life in jail and adapting one’s lifestyle to make one’s time there as tolerable as possible.

1977		E. Bunker Animal Factory 106: Ron patted the roll of flesh that fell over Earl’s waistband . . . ‘What’s that?’ ‘Good jailin.’.
1983		N. Heard House of Slammers 30: He’d started jailing at eight years old – for playing hookey from school.
1990		S. Morgan Homeboy 123: Jailin’ was an artform and lifestyle both. The style was walkin’ slow, drinkin’ plenty of water, and doin’ your own time; the art was lightin’ cigarets from wall sockets, playin’ the dozens, cuttin’ up dream jackpots, and slowin’ your metabolism to a crawl, sleepin’ twenty hours a day. Forget the streets you won’t see for years. Lettin’ your heart beat the bricks with your body behind bars was hard time. Acceptin’ the jailhouse as the only reality was easy time. Jailin’.

2. wearing one’s trousers in such a way that a few inches of one’s underwear is visible; such a fashion was very popular among black youth and their white imitators in 1990s.

1993		Eble Campus Sl. Oct.
1997		P. Cornwell Hornet’s Nest 3: He was jailing, jeans at low tide in that cool lockup look of six inches of pastel undershorts showing. The fashion statement got started in jail when inmates had their belts confiscated so they wouldn’t hang themselves or someone else.
2002		J. Lerner You Got Nothing Coming 158: The end fashion statement is called ‘jailing it’ — a five-to-eight-inch revelation of white boxer tops precariously embraced by the string tightened pants below.

3. serving time in the punishment cells.

2000

Other Side of the Wall: Prisoner’s Dict. July 🌐 Jailin’: (1) Someone who’s in the hole (aka in jail).

4. of a prisoner’s friends or family, visiting regularly.

2000

Other Side of the Wall: Prisoner’s Dict. July 🌐 Jailin’: [...] (2) Wives or girlfriends who visit regularly.