Green’s Dictionary of Slang

1. (US prison) to electrocute; also to beat up severely.

1971–2

C. Shafer ‘Catheads [...] and Cho-Cho Sticks’ in Abernethy Bounty of Texas (1990) 197: barbecue, v. – to kill by electrocution; also to beat severely.

2. (US black/drugs) to smoke marijuana.

2000

W. Shaw Westsiders 12: On the dub [...] we barbecue maybe four or five times a week.