Boys = MUD

How is it that I can look around and not see any mud in sight, but minutes later my boys are covered in it?!? I swear my boys were blessed with a top of the line mud-finder. Unfortunately I have no clue how to disable it. I'm not sure if you can see this well, but both of their rear-ends are black from playing in the mud. There was one faulty sprinkler in the very back corner of my parents yard. They found it and sure had fun!