Red XIII
Nanaki HATES being called Red XIII and I completely understand why. Unfortunately, my drunk-self doesn't seem to understand why, and openly blurts out the moniker left and right, all night long, even when he's within an earshot...and even after he's begged and pleaded with me to stop.
Long story short, even an ex-Shinra soldier, first class, can be a jerk when drunk.
Note to self: lay off the alcohol when Nankaki is going to be around, and make sure to separate yourself from him if he happens to show up out of the blue after you've already put down a few hours into partying.