Hit it untill it stops moving
When passing a joint you do not want back, it is courtesy to estimate the percentage left before the joint will burn you. You may also say "hit it untill it stops moving" to indicate the person being passed said joint may continue smoking it untill there is nothing left, or untill they are satisfied.
Billy- "here you go man, it has about 10% left in it, you can hit it untill it stops moving, I'm good."
Tom- "sweet, thanks brah."
Tom- "sweet, thanks brah."