An Opti-pess is someone who always assumes the worst is going to happen so that they’ll be pleasantly surprised when the worst doesn’t happen. Or if the worst case scenario does occur they are prepared to deal with it/have the satisfaction of knowing they were right.
Basically a pessimistic optimist or an optimistic pessimist
Friend: I’m worried about you. You only focus on the negative things and assume the worst of everyone and everything
Me: Oh! Don’t worry about me! I’m an opti-pess, I’ll be fine !