Why someone takes the valve caps off all 4 tires of your car?

They needed them and were to cheap to buy their own. 

Just to be jerks.  Sometimes when they're changing my tires, they forget to put them back.  A week ago I got three used tires, and I had to tell the guy three times to replace them.  Geez.

Little kids. Maybe me. When I was 4 years old I put a piece of broken glass behind the tire of the neighbor's car. Why? I wanted to see what would happen when the tire exploded. My mother ruined the experiment when she told me to take it away.

The kids wanted to see if the tires would go flat without the caps. Science!!!

It's usually the lazy high school drop out that changes your oil.