I don't have this problem chronically but I did have it once. My stepmother was accusing me of something and since I wanted to keep my mouth shut and not yell at her for being an uncompassionate, heartless jerk, I bit my lips and it sort of looked like I was smiling. Then she yelled at me, saying she knew I was right and had lied, because I had bit my lips and smiled (which I hadn't, not on purpose). I hadn't lied about anything. I wasn't manipulating them. I had been pretty damn open and honest about everything.

I don't know how to stop it, but I just wanted to say that all of us have an "inappropriate" reaction from time to time, and it's not because we are bad people, it's just because we don't know how to react and, I think, that we sometimes laugh or smile because to express the other emotions, the negative emotions we are truly feeling, would destroy us because they are so strong.

Seesaw