flugtag
n.— «More than 30 human-powered aircraft designs will take part in Red Bull’s Flugtag competition on Aug. 3, behind the Canadian Museum of Civilization in Gatineau. It’s part air-show spectacle and part Jackass stunt. Flugtag is a German word meaning “flying day,” as in the day you fly off to holiday. The competitions have been held in major cities around the world. Teams of five people must build and “fly” a contraption with a maximum wingspan of nine metres and a maximum weight of 200 kilograms.» —“It’s a bird, it’s a plane, it’s Flugtag” by Tim Shufelt Ottawa Citizen Aug. 2, 2008. (source: Double-Tongued Dictionary)
Further reading
Language is always evolving, and that’s also true for American Sign Language. A century ago, the sign for “telephone” was one fist below your mouth and the other at your ear, as if you’re holding an old-fashioned candlestick...
Carol in King of Prussia, Pennsylvania, recalls her mother using the word meckle to mean “mess around with,” as in stop meckling with your cereal and eat it! Or if a sewing project was too complicated, she’d say there was too much meckling involved...
While Flugtag may be used to mean “the day you fly off to holiday”, this meaning wouldn’t have spontaneously come to my mind. By far the primary meaning is “air show”. (I’m a German native speaker.)
Also, the famous Austrian energy drink company held the first Red Bull Flugtag in 1991 (dixit Wikipedia).