After a long way, a truck driver ends up in front of a tunnel. He can not get through without severely damaging his truck, because the tunnel has a height of 3.00 meters, while his truck has a height of 3.01 meters. The driver would like to pass the tunnel because the other way will take him at least 1 hours. Suddenly he gets a great idea, he immediately starts doing some things and after 10 minutes he is back on track on the other side of the tunnel. What was the great idea of the truck driver?

What has four legs and only one foot?

It happens once in a minute, twice in a week, and once in a year?

What is it?