Speaking from experience, weed is the only drug I think I ever had the choice of "turning it off" when I wanted to. I could be high as a kite one minute, then choose to sober up. Sure, bloodshot and/or glassy eyes are still there (along with smelling like weed), but anyone who has smoked alot knows what I am talking about. And for those who have never smoked, you can only get so high, and that depends on the quality of the weed. I can remember smoking an ounce of pot in one sitting with my brother and a few friends back in the mid 80's, but a few hits of today's weed would make you higher than all the weed you could smoke 30 years ago.