Waugh!
Some things just get the adrenaline going. For example, leaning back in your office chair, stretching and yawning, then spotting a lil brown spider a couple feet above you, lowering itself from the ceiling tiles on a direct course for your open mouth. I'm just glad nobody walked past my office door at that moment to see the high speed move-chair-back-and-jump-out-of-it maneuver I did.