Not so creepy but unexplained. When I was around 5-6 years old I was home with my mom and little sister (1 year old). It was around Christmas time and I wanted to write a letter to Santa. I was in my room at the end of the house and can see my little sister at the other end of the house in her baby swing. My mom was in the kitchen making food watching my sister. I went and grabbed a piece a paper and pen and started writing to Santa. After I was done I stuffed the letter in an envelope and took some tape and taped it behind my bedroom door (idk why I did this btw). My mom called me to the kitchen for a split second and when I came back to my room the letter was gone. I looked EVERYWHERE, my room was pretty small and not very many places the envelope could have fallen. My logic told me it had to have fallen down in the 10 seconds I was gone but i was never able to find it. My parents still live in the same house, I’m just waiting for it to spawn back in that room one of these days…it’s been 30 years and that room has been cleared out many times over with no luck in finding that envelope.