Green’s Dictionary of Slang

1. (Aus. prison) masturbation.

1990

Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Highland fling. Masturbation.

2. (N.Z. prison) an injection of drugs.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 87/1: highland fling n. an injection of intravenous drugs.