A heckler interrupted John McCain while he was giving a speech on energy at Missouri State University. The heckler accused John McCain of supporting more tax subsidies to oil companies than any other Senator this year. The heckler was heard shouting, "how can you be trusted? How can you stand up for the policies of the current administration?"
The Springfield News-Leader has more details about John McCain's energy speech here.
This video is from CNN.com, broadcast June 18, 2008.