I always wipe the sweat off my hands on my pants between stocks. (most people do)
I do strange tongue movements during matches.
I have been known to talk a lot of **** when playing against my cousin
My expression is usually more or less calm, and expressionless. I lean forward with my eyes all zoomed in.
When I lose a stock, I will shake my head or look down at the ground.
I'm prone to yelling like a lunatic if anything outrageous happens. Since I main Luigi, if I get a misfire I get this big smile on my face.
If / when I get down to my last stock I sometimes shout "Ban-Kai" (lmao), before going all out serious!!!
Sometimes when I get really pissed off, I make up my own curse words like the AVGN, or the Tourettes Guy. But mostly around friends.