Their favorite activity is to hide under a kids bed, then just as the kid is ready to drift off to sleep they sneak up under the bed covers and grab the kid by the foot. If the kid is not completely scared they will try dragging him out of bed. On other occasions they become invisible and pull the sheets off the kid when they are awake. This makes the shhets look like they are moving on their own.
Johnnies mom: What's the matter dear?"
Johnnie; The Clipcloppers and Cottas are grabbing my feet"
Johnnies mom; " Don't say that ever again or the police will come and lock you up in the lunatic Asylum for the rest of your life."