(qualifier:directed at a horse) move on!, go faster!
Gee up, Dobbin, Gee ho, Dobbin, Gee up, Dobbin, Gee up, and gee ho - o - o! 1850, Charles Dickens, chapter XII, in David Copperfield:
There he sat and kicked away and cried: " Gee up, gee up! " to his nag. 1886, Peter Christen Asbjørnsen, translated by H.L. Brækstad, Folk and Fairy Tales, page 223:
He kept on cracking his whip, and calling out, "Gee-up, my five horses!" 1996, Andrew Lang, The Yellow Fairy Book, Big Klaus and Little Klaus,, →ISBN:
"Gee up!" The horses roused themselves and pulled the light carriage along as though it were a feather 1961, Nikolaĭ Vasilʹevich Gogolʹ, chapter 1, in Dead Souls, →ISBN:
(slang) To excite in order to try to achieve a desired result.
"US fund manager Eric Knight has a fearful reputation as a shareholder activist, geeing up underperforming managements at Royal Dutch Shell and Suez." – HSBC: activist pounces, The Week, 15 September 2007, 631, 43.