In Spaceballs Yogurt teaches Lone Starr to use "the Schwartz". Schwartz is a German/Jewish name meaning "dark" or "black". Yogurt is literally telling him to use the dark side. Yogurt is a Sith Lord and Lone Starr his Sith apprentice

It basically comes from words meaning "dark, black, dirty or illegal".

Usually used as a nickname for people with dark skin or dark hair.

I don't think it was Mel Brooks intention for it to be like that, but it is what it is.

---

Yogurt is Palpatine

Starr is Darth Vader

and Darth helmet is Count Dooku. Yogurts secret apprentice leading the "bad guys" military forces. When the time comes he lets his prospective apprentice destroy Darth Helmet to help turn the stronger apprentice farther towards the Schwartz. The dark side