Perhaps you missing bowl is a sign saying DONT FUCKING SMOKE UP BEFORE DRIVING YOUR CHILD TO SCHOOL. I like weed as much as the next guy, but seriously dude either learn some responsibility!
EDIT: sorry to come off like an ass but this is the kind of behavior that will keep pot ilegal... Lets say someone had cut you off and you hit them, thankfully no-one was hurt but you all go and get checked out. Even though you werent incapacitated they find thc in your blood work. Now theres charges filed, it makes the news and your fender bender that you didnt even cause is the top story on drug enforcement. Realy man shit like that happens. (yeah yeah counter arguement: traces stay in your system for a long time... but lets say you would have had an extra half second of reaction time if you hadent just toked)