Hashish
The "overdose" can cause nausea, vomiting, dizziness, hallucinations (unique compared to any other class of hallucinogens), disorientation, strong sedation, pale skin, sleeping (up to 12 hours), and in rare cases short comas (up to 2 days). The person experiencing the "overdose" generally ends up fine. In bad cases, they may end up in a hospital from thinking they're in danger, or for someone else mistaking their symptoms as dangerous.