The roots of this phrase are founded in Alborz High School in Tehran, Iran.
"Chi" can be a suffix to tie a name with a specific profession or commodity, e.g. FarshCHI for a Carpet Merchant. It may have stemmed from the last name of charismatic Alumni with that suffix in their names!
Doc (or Ostad -- Professor) was a common way for students or Alumni to address each other.
Doc Chi as in Doc --Chi where one might insert a nickname for --.
Doc baChi submitted this item :)