National High Five Day is observed on April 18, 2019. You should celebrate this day by giving a high five to someone. The high five is a celebratory hand gesture that occurs when two people simultaneously raise one hand, about head high, and push, slide or slap the flat of their palm and hand against the palm and flat hand of their partner. The gesture is often preceded verbally by the phrase "Give me five" or "High five".
High Five Day was created by college students at the University of Virginia in 2002. There are many origin stories of the high five, but the two most documented candidates are Dusty Baker and Glenn Burke of the Los Angeles Dodgers professional baseball team on October 2, 1977, and Wiley Brown and Derek Smith of the Louisville Cardinals men's college basketball team during the 1978-1979 season. (With material from: Wikipedia)