My wife and I were sued for a cat.
More specifically, a woman stole our cat, then sued us after we got him back. He entered our lives when he ran into our upstairs neighbor's apartment and hid behind their washer/dryer. My son, at over 6' tall, was the only one whose arms were long enough to reach him. My son pulled him out, brought him downstairs, and handed him to my wife, at which point the cat melted into her arms as if it was the first time in months that he'd felt safe.
We took pictures of him and posted "found" posters around the neighborhood, then took him to the local animal shelter. A week later, when no one had contacted us or the shelter looking for him, we adopted him.
Several months later, someone came to our door claiming to have seen their cat in our window. Since we had three cats, we asked them to describe it. They gave a fairly accurate description of this cat, except for saying that he was a girl. The shelter had neutered and chipped him before adoption, but he was quite obviously male when we first found him! Several days later, a woman came to our door and asked if she could just hold the cat for a moment. My wife's heart went out to her, so she agreed. She handed the cat to the woman, who then took off running. My son chased her, and saw her get into a waiting SUV and drive away. The car looked familiar, so we kept a lookout for it whenever we walked our dog.
After a few weeks, we spotted the woman getting into the same car in the next building over from ours. We called the police and gave them the address and the woman's description. They actually recognized both, having had multiple run-ins with her before. They went to talk to her, and got her to bring the cat back. She showed up with the cat and her three young children, all looking very sad. We promised to go to the vet the next day to have him checked for the chip. If it wasn't there, they could have him back. If it was, they wanted to be able to visit him occasionally.
Well, the chip was there, proving that he was the cat we'd adopted. We informed them, but they never contacted us about visitation. The next contact we had was a summons from Small Claims Court demanding that we either return the cat or pay whatever the maximum dollar amount allowed by Small Claims. Then we got a letter inviting us to have the case tried on the Judge Joe Brown TV show. That ended up falling through because the woman didn't respond to her invitation.
We wound up in court where we had the adoption papers, chip records, and multiple vet receipts, and she had three sad-looking kids and some blurry cat pictures on her cellphone. I think it was all the judge could do to not laugh in her face. At one point during the whole fiasco, I looked up her name in public records. From what I found, I can only surmise that she apparently makes her living suing people.