During Season of the Plunder, he shares a strange drink with Drifter, Mithrax, and Eido. Then in this season, he drinks all sorts of random potions brewed by Eido with crazy ingredients and bizarre reality-warping effects. Now in the Past is Prologue quest finale, when looting the vending machine, he grabs a bootleg tincture he finds alongside Chatterwhite. I find that pretty funny.
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Well technically, with the Ghost always healing, alcohol would most likely have no effect. Unless of course the guardian tells the ghost to let them get buzzed, like how Drifter told his ghost to stop the feeling of hunger.