Green’s Dictionary of Slang

1. to steal [esp. in 1960s radical use, on the Proudhon principle that ‘property is theft’ but likewise with a degree of irony/self-mockery given the 1960s obsession with ‘freedom’ and ‘the revolution’. With further irony, the ‘radical’ use stems f. WWII ‘liberating forces’ who ‘freed’ commodities as well as people].

1946		J.W. Bishop ‘American Army Speech’ in AS XXI:4 Dec. 251: Liberate. To scrounge, or steal; to loot. ‘I liberated a swell gold watch in Mannheim.’.
1969		H. Rap Brown Die Nigger Die! 53: To show the muthafuckas what I thought about the whole meeting, I stole some stuff from out of the White House. I liberated everything I could!
1977		L. Heinemann Close Quarters (1987) 101: Which one a you motherfuckrs got the goddamn grease gun? [...] Come on, which one a you liberated that cocksucker.
1981		A. Payne ‘You Need Hands’ in Minder [TV script] 27: I could go and liberate a nice W Reg Bee Em.
1997		Simon & Burns Corner (1998) 11: Breaking into parked cars and liberating cassette tape players is nothing more than caper.
2006		D. Mitchell Black Swan Green 78: Plebs ‘pinch’, I ‘liberate’.
2013		S. Barber ‘Killer, Duck and The Boys’ in ThugLit Apr. [ebook] After Rip liberated a wallet, they sat [...] watching the girls .

2. to eat or drink.

1990		R. Doyle Snapper 144: Jimmy Sr liberated the rest of the burger.
1991		R. Doyle Van (1998) 423: May as well liberate these an’ anyway, said Bertie, – wha’. He got his sixpack out of its paper bag.