Green’s Dictionary of Slang

file n.2

[a laboured pun on Peterfile/paedophile]

(N.Z. prison) a paedophile; also used as a suffix and combined with the subject’s given name to identify a given paedophile.

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 68/2: file n. 2 a nickname for a paedophile, most commonly added after an inmate’s first name to identify him as a child molester, e.g. JJohnfile .
[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 68/2: file n. 1 (also filer) a child molester, from ‘ paedophile’ .

In compounds

filing cabinet (n.)

(N.Z. prison) those adjacent cells occupied by child molesters.

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 68/2: filing cabinet n. a group of cells belonging to, or the general area of a prison compound commonly occupied by, inmates in prison for child molesting.