Green’s Dictionary of Slang

1. (N.Z. prison) in pl., to steal.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 185/2: teabags v. to steal.

2. (UK prison) to give multiple stab wounds.

2007		N. ‘Razor’ Smith Raiders 185: It is relatively cheap [...] to get someone tea-bagged (left with plenty of perforations).
2009		J. Stahl Pain Killers 175: There’s chicks out there who wanna drink mailman pee, get tea-bagged by fat guys.

3. in non-prison context, to wound.

2012

A. Bergen ‘Dread Fellow Churls’ in Crime Factory: Hard Labour [ebook] The pistol did a bit of tea-bagging around my palate and almost knocked out one of my molars.