I have a dog named Smokey. He's a black labrador, and he's waaaaay too big for his breed. He chases cars, bicycles, animals, pedestrians etc. He once broke my mom's finger after tugging on the leash too hard. When he wags his tail, we have to make sure there are no drinks nearby, since he WILL knock them over.
He's a nightmare. I still love him, though. ^^;