Shot-clog \Shot”-clog`\, n.
A person tolerated only because he pays the shot, or reckoning, for the rest of the company, otherwise a mere clog on them. [Old Slang]

Here’s some more info …

a bore tolerated only because he or she pays the shot

Examples:

I’d planned to reimburse Jerry for the meal via PayPal, but after sitting through a lengthy evening of him holding forth on myriad topics, I decided it would be an unfair challenge to his reputation as a shot-clog.

“Alas! I behold thee with pity, not with anger: thou common shot-clog, gull of all companies; methinks I see thee walking in Moorfields without a cloak, with half a hat … borrowing and begging threepence.” — John Marston, Ben Jonson, and George Chapman, Eastward Ho!, 1605

Did you know?

The shot in shot-clog refers to a charge to be paid. It’s a cousin to, and synonymous with, scot, a word likely only familiar to modern speakers in the term scot-free, meaning “completely free from obligation, harm, or penalty.” The origin of the clog part of shot-clog is less clear. Perhaps it’s meant to draw a parallel between a substance that impedes a pipe’s flow and a person who impedes a good time; or perhaps companions’ tabs accumulate before the shot-clog as so much dross in a clogged pipe, while the shot-clog yammers on unawares. The 17th-century playwright Ben Jonson was particularly fond of shot-clog, and while the word is no longer in regular use, it might work for you as a suitable old-time insult for that person in your party who is fine to have around so long as they pick up the tab.

Word of the Day: Shot-clog | Merriam-Webster