I'm pretty sure it happens with all teachers or professors - probably with all people, but most don't have the opportunity to talk to you day after day for hours on end - they have one or two "crutch words" or phrases that they use repeatedly, often without thinking and sometimes apparently without context. My Greek professor, for example, uses the phrase "rough and ready" to refer to the book's translations of vocabulary words or case usages, his point being that Greek is much more subtle and variable than our text makes out.

What actually prompted me to write this post, however, was his use today of the word "copacetic," which was possibly my high school volleyball coach's favorite word ever. She used it as a general sort of positive interjection, e.g. "Is that play clear? Copacetic!" Dictionary.app offers this definition:

copacetic |ˌkōpəˈsetik| (also copasetic)
adjective informal in excellent order.

Interestingly, the word has no known origin (my etymological dictionary doesn't even have an entry for it), so you can use it however you want.