mysterious holes

Every tank top I own develops these holes.
Even some of my t-shirts.

I.don't.get.it.

For the life of me, I can't figure out where they come from, or what causes them.

Baffled.

And a little annoyed.

Have you ever had this happen?

Any ideas what could be causing them?

I've ruled out a belt buckle - I rarely wear a belt, and it's higher than where a buckle would rub...

Maybe it happens in the laundry?

Or maybe I have an evil, little gnome living in my closet that likes to gnaw holes in my shirts.

I should set a trap.

I just wish I knew what caused them.  Grrr.