The Beast of Bourbon is a hallucination created by Marten after heavy consumption of bourbon. It appears in the bathroom of his apartment. Similar to the Tequila Monster, the Beast of Bourbon is a large, bipedal, weasal-like creature, though its primary color is a pale yellow, with blue spots and dark green eyes. It is perhaps slightly classier than its hallucinatory relative, as it is seen wearing a bowler hat and reading Drunken Hallucination Weekly.
He apparently knows a nine-foot pterodactyl named "Gary", which requires even more alcohol consumption to see.