Not a teacher
Which means s/he doesn't want to talk during dinner about school or anything relating to their jobs. That s/he wants them to talk about other subjects than what they do for a living.
It can be used when talking to the boss or customers. For example you are talking to the boss and you say "A bunch of us got together after work last night and it seemed like we ended up talking shop."
Which means they ended up talking about the (their) job (what they do for work).
Student or Learner