Mileage????

Note: These P.J.'s are only one season old and this child owns 2 pairs of footie P.J.'s.  Yes, they were brand new when footie P.J. wear'in weather began a few months ago... and, no, the other pair did not fare any better than the pair depicted. 
Can someone tell me what this child does to make his P.J.'s look this way?  Clearly I am missing something, because during most of his waking hours, C wears socks and shoes... or he's barefoot.
Hmmmm...