Green’s Dictionary of Slang

vaccinate v.

In phrases

get vaccinated (v.)

(US) to have a drink.

1876

St Louis Globe-Democrat 19 Jan. n.p.: The party arrange themselves at the bar and are invited [...] to ‘have some whisk,’ or ‘take a smile,’ ‘have one,’ ‘take a ball,’ ‘take a hist,’ ‘take a horn,’ ‘take a noggin,’ ‘get vaccinated,’ all of which mean that one and all shall have a drink.