I've smoked some Snow White before that made me keep seeing flecks of colors everywhere whenever I blinked. In college I tried some Thai stuff that made my ears ring in this odd chime noise. Man, I've smoked lots of weed and lots of kinds of weed and let me tell you: There is some crazy shit out there.
REGARDLESS of my own personal experiences with hallucinations, I must say that they are never major ones. It's not like acid or anything, it's just your brain filling in the missing pieces. Indeed, if you study how the brain learns and memory then you will have run into this effect before. People often take perception for granted but what we see, hear, and feel is not necessarily what actually is there. In fact, if we DID NOT have this ability then whenever we looked at anything from a different angle then we would not recognize it. It's the science behind perception.
When you smoke weed, your brain becomes a little bit fuzzier and paranoia leeks into your thoughts. (I sincerely hope you will agree with me on that much.) So, let's just say you are stoned and walking around outside at night. From the corner of your eye, you see a sudden flash of white and you move and whip your head around to see what it is... But by the time you focus, it's gone. Because you are high, it is easier to jump to a different conclusion than you might have made while sober... Or hell, you might make the same wrong conclusion about the light while sober depending upon circumstances.
Later on, when you try and describe what happened to someone, your brain fills in what it believes that light was. For this argument's sake, let's just say you thought it was a ghost. Snaps and dang! But wait, you are going to make the claim that the light MUST have existed and that is what prompted the response... Which means it is not a hallucination and therefore just confusion because there was still a stimulus that actually exists.
Okay, then let's get down a little more with a classic, silly example from a movie that can instantly be related to: Pineapple Express' phone scene
See how stupid this discussion has gotten? Listen, I am glad that you like pot and you want to see it legalized. Cool beans... But you don't know all the facts and you really are not good at arguing them. I am begging you, PLEADING you to never again argue for legalization in public again. You hurt the cause.