To'kai came to be when a dude tried saying "so high" with his dry lips and ended up saying to'kai. Basically it is used when you've smoked so much and can't smoke no more weed. Often used as a sign to others that you're alive'n'kickin but are currently in "stand by" mode.
<Jericho> Daj rizlu da motam. (Let's roll another one)
<Vlax> I'm to'kai.