I usually try to come up with a friendly smart-assy response to trivial banter that irritates me. If someone asked me to smile, I would just tell them that I was saving my smiles for special occasion or tell them I charge by the smile.

Personally I don't think it's a bad thing to smile at a funeral, I smile as a nervous reaction... I smile a lot. I may even have a resting smile face but this isn't the life you want either. People always think I'm being fake, up to something, or just plain weird. On days I didn't smile people would start asking questions, so I would then just smirk and laugh to myself all the time... people give you funny looks but they don't ask a lot of questions.

Make sure to have fun with life and try to reflect good thoughts and feelings back to people who test your patience. It's not all their fault, sometimes we unknowing push each others buttons... like subconsciously some stranger will magically know the one thing that will muck up your day. It's all really kinda of amazing if you look at it.