My dog is scared of my older brother.
He's a rugby player, so he's big, and has a fairly dominating presence.
If anyone tells the dog to do something, he normally obliges, as he's fairly well trained.
But occasionally he gets out of hand. He quickly settles down if anyone takes control of him.
However, if my older brother takes control of him, he instantly drops to the floor, turns on to his back, exposing his belly and chest, which is the submissive position for canines.
And he'll quite often do this and urinate.
He'll be surprised and scared when my older brother comes back from University in a few days.