The 'Mind Size' meme features a digitally altered image of YouTuber Markiplier with an unnaturally enlarged forehead, symbolizing massive intelligence. Often accompanied by captions like 'Mind Size: Mega' or 'Mind Size: Large,' it is used to ironically praise someone for a clever idea, a lucky guess, or a 'big brain' move that might actually be nonsensical. The image originated from a Photoshop edit of Markiplier's face and gained massive traction on Reddit and Twitter in early 2020. It serves as the spiritual successor to the 'Expanding Brain' meme, providing a concise way to react to displays of extreme logic or accidental brilliance.