Idle hands are the devil's workshop, or so my folks would like to remind me when I was growing up. Now, there's scientific evidence of just that.

Last summer, my nephew, the college student, landed a job driving a school bus. The company loves him, and it happily took him back during his winter and spring breaks. Though he had a spotless driving record, he had never driven a bus before. His primary qualification? He passed the company’s drug test. Dozens of more qualified drivers could not.