We all know how dangerous it is to drive when you're really tired.

Unfortunately, I've fallen asleep at the wheel a few times.  In one instance, I worked overnight and had a 70 mile drive home.  I don't remember about 40 minutes of that drive, but I must have been in some "sleep functioning" state because I didn't wreck or hit anything.  In another instance, I actually sideswiped a car (naturally, I was less than 2 minutes from home).

Obviously falling asleep at the wheel is a bad thing.  But it's a little less serious ... and a lot more funny ... when it's a kid falling asleep driving his motorized truck.