Its something about some boys who came across something in the drug running they shouldn't have and ended up dead. Somebody made a documentary on the whole thing that was pretty informative, i'll see if i can find it...
Edit: I found this link about the whole Mena thing. Its mostly wild conspiracy, but the basic connections are in it. I don't buy much about any CIA involvement and what not, but basically there were some connections among Clinton, people involved in the drug trade, the Rose firm, etc...The whole situation then was extremely shady, and while I certainly don't think Clinton was running drugs through the state and killing off teens, I think there's a strong chance he knew people who were, and didn't do much about it. We'll never know now, but if you come across some of the less-conspiracy theory type articles and interviews, its pretty interesting stuff.
http://www.wealth4freedom.com/truth/13/Mena.htm