I stopped when I was about 11 or 12 because my Mum and Dad thought it was "time" I should know because I was starting to get sarcastic and making my sisters more towards not believing in "Santa" too.
Also, on Christmas Eve, my Dad used snow spray on his work boots and printed them onto the rug in front of the fireplace. It was all starting to get a bit too obvious.
It all happened 7162 days, 23 hours, 39 minutes, 59 seconds ago...
Santa Claus? That's segosa. So stop not believing in him. The only thing you believe is that he gives you presents. He just gives you the finger in reality.