The Knock Knock meme, specifically the Grim Reaper door-to-door variant, is a powerful visual metaphor for the inevitable end of trends, companies, or celebrities. Each panel shows the Reaper leaving a bloodied room—representing a 'killed' entity—and moving to the next door to deliver a final blow. It gained massive traction on platforms like Reddit and Twitter as a way to comment on market shifts, such as the evolution of social media apps or the decline of movie franchises. Its dark humor and sequential storytelling make it one of the most versatile templates for internet commentary.