Green’s Dictionary of Slang

energiser n.

[[‘From the Australian television advertisement for Energiser batteries in which Jacko, the front-man, shouts 'Oi!' as his trademark expression. Oi is a common skinhead greeting’ Looser 2001]

(N.Z. prison) .

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 65/2: energiser n. a skinhead.