Not really a santa story, but a christmas story. It was on Christmas eve, I remember that much. Mom had set up my bed in the living room for some reason or another (most likely so she could sleep on the couch and watch over me), and I was ill with a really bad cold. I had to prop myself up with pillows and everything. I remember being worried I wouldn't be able to sleep because of my cold, and that Santa wouldn't come.
I.... promptly fell asleep. Yes 'Santa' did come that year

Another story I remember was when I was like... eleven. I really didn't believe, I just kinda pretended for mom's sake. Mom and I were at Grandma's on Christmas Eve, because we alternated staying there between mom, and her sisters until we got Grandma moved into our apartment. We were both still awake and watching CSI (I remember because it had just come out and we were OBSESSED) and mom goes upstairs, and comes down with presents in her arms.
"See! I told you Santa wasn't real!" I hissed.
"Shut up and lay down," she muttered back.
She makes a few more trips all the while hissing at me to 'lay down' and I am just grinning like a loon, trying not to laugh, because I don't want to wake my grandmother.
Best christmas ever.