It started one day in my bedroom. I was chilling somewhere, and my sister was on her bed. And out of nowhere, I just called her Kitty-Chan. And it stuck. This was fairly recently, too. Mother's Day Weekend, I believe.
For this one, I was just chilling on my mom's bed with her cat, Toni, in my arms. She was busy kissing me because I gave her a pat on the head, and I just randomly announced "Toni Kisses!" and she became Toni Kisses; a nickname out of many others.
"I don't want a Kitty! I want a puppy!"
This is my favourite nicknaming story of all--even though I didn't come up with it, and it didn't happen to me. So basically after my sister was born, my grandfather held her and was coming up with nicknames for her. He said a couple of names, but when he got to Kitty, my eldest brother, James, exclaimed, "I don't want a Kitty! I want a puppy!" So Kitty stuck. And James got his puppy, almost a decade later.