Zackass: an internet troll whose opinions are always more equal than others; one who will put you down because he has 'served his country' and believes that you have not; one who will never admit he is wrong, despite overwhelming evidence to the contrary
just because your opinion differs from mine does not make it better, or more valid; stop being a Zackass
Having extreme qualities of what it is to be a jackass, or something close to it. If someone around you is fucking around and acting like a dumbass, refer to him as a 'zackass'.
'When we were washing cars for a school fundraiser last weekend, I told Zack to go and get the towels, so he decides to dance on them. *facepalm* what a zackass.'
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.