Karma just means "Action". It's not some kind of good deed pention plan for the afterlife. Nor does it consider morality. It is completely non-negotiable, unstoppable, fluid, and devoid of any purpose or agenda.
It's not keeping a tab on us, or any kind of score. It doesn't care what you did last summer, doesn't spell vendetta with a 'V' You cannot feel it, or touch it, and you can only observe it's effect on the World, if you can find a place of perfect stillness to watch from.
It is unmitigated and uncompromising. It will not notice you, but it is inescapable. It is the first movement of the first molecule of matter. It is a Principality, and can't be diverted, invoked, avoided, or streamed. It moves simultaneously through all things, and everything resonates to it.
Karma will not 'reward' the man who spends his life doing "good" deeds, and it will not punish the wicked. It doesn't care if your name is Adolf Hitler, or Earl Hickey. It does not "come and go" it just is. It's colours are not like your dreams, red gold and green. It's not your lover, or your rival.
We may be oblivious to it, but we're still wrapped up in it's dynamic. So we really are in a Karmacoma. (Jamaica in Roma) It rolls over you, like a massive attack. Tricky too. http://www.youtube.com/watch?v=aq7IPovx9Ug&feature=related