If you have any more details or another way to describe the piece you're looking for (like the genre, when you heard about it, or a brief summary), I'd be happy to try and help further!
You're looking for a guide to "Ojisan de Umeru Ana" (also known as "The Hole in the Wall" or "" in Japanese) but in English! ojisan de umeru ana english
The phrase has bled into manga and anime, often used for dark comedy. In series like Aggretsuko (which brilliantly satirizes Japanese corporate culture), the background extras—the silent, tie-wearing, mustached men in the corner—are literal Ojisan filling holes. If you have any more details or another