Green’s Dictionary of Slang

gusto n.1

[SE gusto as used in the 1966 advertising slogan for Schlitz beer, ‘Schlitz. Grab for the gusto!’, an abbr. of the orig. line ‘You only go around once in life, so grab for all the gusto you can.’]

(orig. US black) beer.

[US]D. Claerbaut Black Jargon in White America 67: guston. beer [...] v. to drink beer.
[US]B. Hamper Rivethead (1992) 56: Drinking right on the line wasn’t something everyone cared for. But plenty did, and the most popular time to go snagging for gusto was the lunch break.