What does cannabis do to you?

It has a painkilling effect, can cause deep relaxation and an altered perception of time it will stimulate your appetite (munchies)and can cause fatigue and disorientation. if you smoke loads you can make your self sick known as a 'whitey'.
My answer:
The effects are different for every person. Some common effects also include a deficiency in estimating distance (if you smoke a LOT of marijuana), and a distorted sense of time, not in the sense that everything is in slow/fast motion, more in the sense of, "Woah, only 3 minutes have gone by." These effects are caused by increased THC-laiden blood flow to the brain, which increases oxygen flow, which also helps create the effects associated with cannabis intoxication.