1. Another way to say "idiotic". (If stupid peoples' skulls were coffee cans, you would be able to hear new thoughts rattling around in the empty space where their brains should be.)
Guy #1: WTF? I just asked the bartender for a shot of Jack and he gave me vodka rocks.
Guy #2: Dude is permanently rattleballs. We should ask for a pitcher of gin and see what he does.