Denmark

When Nazi Germany occupied Denmark in 1940, chemist George de Hevesy dissolved two colleagues' Nobel Prize gold medals in aqua regia and left the yellow liquid on a shelf. The Nazis never noticed it. After the war, Hevesy recovered the gold and the Academy recast the medals.

Bluetooth is named after Harald "Bluetooth" Gormsson, the 10th-century Viking king who united Denmark and Norway—as the tech would unite PCs and phones. Its logo merges his initials in runes ᚼ and ᛒ. A placeholder name, it stuck. The nickname likely came from a dead, bluish tooth.