shamelessly checking out a dude's really ripped sexy biceps; admiring a hot guy's hot arms, usually involves touching them sensually or staring at them like the piece of meat that they sometimes are. lol
girl: do you lift a lot? your arms look delicious...
guy: yeah, you are totally Cassieing me right now
girl 1: omg did you see Mark's arms at the gym today?!?
girl 2: you know i did, even with the farmer's tan i was still Cassieing so hard
When people get pissed off at you because you type with CAPS LOCK on and think that you're yelling at them but you're really just trying to emphasize your point.