The origin of this term is uncertain. It is believed that it is a reduplication of the name given to a rent party in early 20th century USA. These parties were impromptu affairs which were organized to raise money to pay rent and at which a small entrance fee was charged.
This term was first recorded in print as the title of Clarence 'Pinetop' Smith's 1928 recording, which includes these lyrics:
I want everybody to dance just like I say
And when I say 'hold it there'
I want all of you ... to stop
And when I say stop - don't move
And when I say git it
I want all of you to do a _______ _________.
Name this term being talked about!!
(Try to answer without googling)
Shrey and Chithananda got it correct as usual.