jitterbug: a lively popular dance during the 1940s, performed to swing music
The jitterbug may have been so-named because the highly energetic dancers looked like they had the jitters. The jitters—that is, extreme nervousness—first became a condition in the 1920s. Where the word originated is unknown.
A jitterbug was a jittery person before it was a dance. Musician Cab Calloway popularized the term with his 1934 song, "Jitter Bug," about a man who "has the jitters ev'ry morn" from drinking too much alcoholic jittersauce.
By the late thirties a jitterbug was a jazz and swing fan. According to the Times of London for Jan. 7, 1939, "in the U.S.A. there is a class of people who sit listening in hysterical excitement to what is called 'hot-music' . . . Americans in their forcible language call them the 'Jitter-bugs'. The jitterbug dance soon followed, along with the verb to jitterbug. Dance marathons during the Great Depression were sometimes called jitterathons.