Check out this story from ThinkProgress:

“I would suggest moving back,” Bush said as he climbed into the cab of a massive D-10 tractor during his visit to a Caterpillar factory today. “I’m about to crank this sucker up.” Newsweek notes, “As the engine roared to life, White House staffers tried to steer the press corps to safety, but when the tractor lurched forward, they too were forced to scramble for safety. ‘Get out of the way!’ a news photographer yelled. ‘I think he might run us over!’ said another. … Even the Secret Service got involved, as one agent began yelling at reporters to get clear of the tractor. Watching the chaos below, Bush looked out the tractor’s window and laughed, steering the massive machine into the spot where most of the press corps had been positioned.”

This incident reminds me of Jerry Seinfeld's joke about elderly drivers backing out of the driveway without looking for oncoming cars (and which I often say to myself): I'm old. I've lived my life. I'm backing up. In case you're wondering, Caterpillar factories unfortunately do not make caterpillars that, one day, will turn into butterflies. They just make tractors.