[2019] The "Threat Level" shotgun is a reference to "The Office" if you didn't know already

The in-game subtext for the Threat Level is "Hold on Til Midnight" (Threat Level Midnight) and there is a triumph to get kills with the Threat Level called "Clean up on Aisle Five" which references Michael's line from the movie "Looks like there's gonna be a cleanup on aisle five!"