What does he DO to his pants?

This picture shows the normal state of the boy's pants: patched, and patched again, and then ripped again.

The pants below in the picture are the new "Iron Knee" pants from Lands End.  With the hype that they were basically indestructible, I had to order some.  Unfortunately, he seems to be taking the new pants as a challenge, to see if he can rip out the knees.  He puts them on and slides across the floor on his knees.

Sigh.