Green’s Dictionary of Slang

1. (US) to beat up [also linked to tank v.¹ ].

1947		I. Shulman Amboy Dukes 66: He had tanked Crazy for kidding around with his kid sister.
2003		Brummagem Dict. 🌐 tank vt. to hit, beat or thrash.
2012		J. Fagan Panopticon (2013) 190: This will be great, we will fucking tank youz cunts.

2. (Ulster) to administer a paramilitary ‘punishment beating’.

1999

Guardian 2 Feb. 16: What happens when you get ‘tanked’ is that four or more freedom fighters arrive at your door, drag you to a secluded spot and beat the daylights out of you.