First of all ecstasy is very dangerous for adults and I'm guessing that on a 5th grader would be much worse. There is an almost a 100% of developing Parkinson’s disease when an adult takes ecstasy just once. This drug is worse than anyone ever thought a few years ago. I'm only 23 years old and I have only been out of college about a year and a half and I'm young enough to remember high school. I have been around it a lot and have heard a lot of stories. I would go to the police or make an anonymous call. If he's running his mouth on the bus, then he won't know who did it. If it's true and he's is really slipping people drugs, then there are a lot of risks being taken. It might be that because he is new he thinks he will make friends this way and it may not be true, but it could be and something needs to be done. If he is lying then at the very least he will learn not to lie.