Green’s Dictionary of Slang

trip n.2

1. (Aus. / US Und.) a prison sentence.

[Aus]Truth (Sydney) 12 May 5/7: He got four years that trip.
[US]A.H. Lewis ‘The Garrote’ in Sandburrs 133: D’ mug who chases in an’ takes a trip for ten, he’s a lifer.
[US]Ersine Und. and Prison Sl.
[US]Goldin et al. DAUL 227/1: Trip. 1. An arrest or commitment to prison.
[US](con. 1948) G. Mandel Flee the Angry Strangers 93: ‘How long a trip?’ Carter asked. ‘Six moes.’.
[US]J. Blake letter 11 Feb. in Joint (1972) 114: Eighteen months this trip (lucky), for kicking in a pharmacy.

2. (US Und.) an arrest.

[US]G. Milburn ‘Convicts’ Jargon’ in AS VI:6 441: trip, n. An arrest.
see sense 2.

3. (US prison) a transfer from one prison to another.

[US]G. Milburn ‘Convicts’ Jargon’ in AS VI:6 441: trip, n. [...] a draft from one prison to another.