Green’s Dictionary of Slang

1. a prison sentence.

1869		Sportsman (London) 7 Aug. 4/1: Notes on News [...] That power he exercised by committing them to prison for two months, after which slight ‘holiday for change of air and scene’ they will return to their home.
1896		A. Morrison Child of the Jago (1982) 114: I once heard of a very odd job in the Kingsland Road that got a fine young man six months’ holiday.
1968		J. Alard He who Shoots Last 107: ‘How long was your holiday Swifty?’ asked Ragged [...] ‘Two years, plus time on for bad behaviour.’.

2. (N.Z. prison) a tablet of LSD; i.e. from the rigours and boredom of prison.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 88/2: holiday n. 1 an LSD tab.

3. (N.Z. prison) confinement to a punishment cell.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 88/2: holiday 2 a period of time spent in the solitary confinement cell.

4. (N.Z. prison) life outside prison (the inference is of recidivism).

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 88/2: holiday 3 a period of time spent living in general society, released from prison.