Someone, mostly males from the ages of 13-19, who run around throwing rocks at people for no good reason. They throw stones, hence the term "stoner".
Benny: "Ya see that boy Jonny walking towards us?"
Me: "Yeah, what about him?"
Benny: "Well rumor has it that he is quite the stoner."
Me: "AAAAAAAHHHHHHHHHHH RUN FOR YOUR LIfe!!!!!"
*takes off running*