The entire film is just Dr. Carroll intentionally misleading his audience; it either didn't happen, or it was extremely exaggerated
Remember, the whole film is Dr. Carroll telling the attendees of a PTA meeting the supposed true story of what happened to the characters of the film. Dr. Carroll is one of those moral guardians who doesn't really know what kids are up to, only that he doesn't like it one bit. He has heard of this drug that the kids are all using called marijuana (or "marihuana"), but he has no idea what its effects are. Therefore, to ensure that his audience hates this drug, he either makes up a story, or slightly alters a story that he found in an old newspaper (it can't be a recent newspaper, obviously, because people would catch on) to make it seem as though marijuana was to blame for the actions of a careless driver (Jimmy) or a maniac (Ralph).- Granted, he's a doctor, and wants to keep people away from a debilitating substance, but it's still laid on far too thick.
The Moral Guardians are the ones who are stoned.
Credit goes to the Nostalgia Critic for this one, but you do have a bunch of paranoid people staring at someone who keeps rambling on about bullshit that never happened. This might not be limited to them, either; earlier in the film federal agents "dispose" of a huge shipment of pot in an unventilated furnace.The drug the kids are on is meth.
Which would explain their behavior after trying to calm down with weed.