Jolly cooperation is a phrase closely associated with Dark Souls, the action role-playing series known for its difficult combat and online summoning system, where players can call others into their world to help defeat bosses. The community adopted the cheerful wording as shorthand for that shared struggle, and it spread through gameplay videos, streams and memes as a lighthearted contrast to the games' dark tone. It remains popular because it instantly signals teamwork, optimism and the relief of not facing a boss alone.