A traveller passes a field and sees a pig with 3 legs. Intrigued, he pulls up to the farm house and asks the farmer, "What's up with that 3-legged pig?"
The farmer gets all misty-eyed and says, "Let me tell you 'bout that pig. A few years ago, we were all asleep when a fire broke out in the house. That pig jumped out of the pen, broke down the front door and woke the family up. He even dragged old Nan to safety, on account a she can't walk on her own anymore.'
The traveller is amazed. "And he lost his leg helping in the fire?"
"What? No," the farmer responds, "but a few months later, we were out feeding the cows and a big grizzly bear charged in. That brave pig came charging out and fought off the beast until we could all get to safety!"
"Oh, so the bear got it's leg?"
"No, no, miraculously he came out of it completely unscathed! And then just last May, I was working under my tractor when the jack stand started to fail. And wouldn't you know it, that pig pulled me to safety right as the rig came crashing down where I had been laying!"
"And the pig's leg got caught under the tractor?"
"Nope! He was too fast!"
"Well, then how'd he lose his leg?!" The traveller cried.