Bush on methamphetamine
The more I think about Bush's jaw-grinding, furious blinking, that strange twitch in his left eye, the restless stalking, and his lunge at Charlie Gibson, the more convinced I am that he's on speed. That would explain why he's blown off his physical prior to the election. He can't possibly take a drug test until the debates are finished.
See http://www.washingtonmonthly.com/archives/individual/2004_10/004878.php#290990