Thomas Crapper Day is an unofficial holiday observed worldwide every January 27, commemorating the death anniversary of Thomas Crapper, an English plumber known for popularizing the flush toilet. Although he did not invent the flush toilet, Crapper made significant contributions to its development and popularization, including several innovations such as the floating ballcock and U-bend trap. He founded Thomas Crapper & Co. in 1861 and opened the first showroom for sanitary ware, helping to establish a market for indoor plumbing. The holiday encourages people to learn about the history of sanitation and consider remodeling their bathrooms. Celebrants often share their recognition of the day on social media using the hashtag #ThomasCrapperDay.