Peed On His Leg

A blind man was waiting to cross the road when his guide dog peed on his leg.
He reached into his pocket and took out a biscuit for the dog.
A passerby who'd seen everything remarked :
- That's very tolerant of you after what he just did.
- Not really, came the reply. I'm just finding out where his mouth is, so I can kick him in the nuts.