It's customary to make a gift of tobaco to elders that you visit. Hau Kola is the greeting (means 'hello friend'. Toksha means 'later' (the Lakota have no word for goodbye).
also DO NOT DRINK ALCOHOL while you're there.
The locals call their home Rapid for short. Example: "Do you live in Rapid?" or "Are you in Rapid on business?" Unlike the folks in San Francisco, the locals in Rapid City don't mind this nickname for their fair city.