Unsolicited advice

Smiling technically fools your brain into being happy, since you are conditioned to smile when happy. It can also act as a weak painkiller since your brain is releasing stuff like dopamine, serotonin, and endorphins when you smile. You could also conclude people who are smiling more often than not are junkies getting high off life.

IMO the best response to that statement is "Then do something to make me smile, like getting out of my sight"