“No shit, Sherlock” is a long-running piece of English sarcasm built on Sherlock Holmes, the fictional detective created by Arthur Conan Doyle, famous for deducing what others miss. The joke is that the observation was so obvious it hardly needed a great detective to spot it. The phrase has been common spoken slang for decades and became a staple of online humor, thriving in comment sections, gaming streams and reaction edits where calling out the obvious is half the fun. Its staying power comes from that universal setup: someone says what everyone already knows.