Molly is mostly black, at least on her back, and I've noticed that when she's been outside in the sun for awhile, she will go over to a shady spot and roll in the grass or dirt too cool off.  The first few times I've seen this, I thought she was just being silly, but she keeps doing it...so it must work.  No other dog I've had has ever done this, so how smart is she to know how to cool off like that?!  Silly rattie.