The Collaborative International Dictionary of English v.0.48:

Tchick \Tchick\ (ch[i^]k), n. [Imitative.]
   A slight sound such as that made by pressing the tongue
   against the roof of the mouth and explosively sucking out the
   air at one side, as in urging on a horse. -- v. i. To make a
   tchick.
   [Webster 1913 Suppl.]