A non-offensive combination hand and arm gesture in which the "Skyfister" will clench his/her fist and raise it as if to fight right about to the top of their head and then proclaims "Skyfist!" Typically used when someone pisses you off in lieu of flipping the bird.
Woah! Did you see that jerk just cut in front of me at the beer tent?? That dude gets a skyfist!
Hey! Did you see Abe today?? Her beard was extra scruffy and just for that she gets a skyfist!