That's A Nice Doggie!
A guy was standing at the traffic lights with his guide dog waiting to cross the road.
Without warning the dog lifted his leg and urinated on his trousers.
The guy bent down and patted the dog's head.
A nearby pedestrian asked him why he rewarded the dog by patting him on the head after he did such a bad thing.
The guy replied that he was not patting him, he was merely trying to find where his butt was, so he could give him a good swift kick.