When my brother showed me the stash of presents in the basement closet. It was our mission every year after that to find the presents before Christmas. My parent’s got VERY good at hiding them, but never good enough.
I think I was seven, and I recognized my mom’s handwriting on the boxes. I think I must have been suspicious before that, though, since I don’t remember it being traumatic.
The trauma came in future years when she insisted on labeling at least one present each to my brother and me as being from Santa even when we were both years past believing. For some reason I found it horribly embarassing. Of course, I found it embarassing for my mom to EXIST when I was a teenager.
Now I think it’s cute, and would probably do the same thing if I had kids, to annoy them if nothing else!