What's the creepiest thing you've ever experienced?

So this happened to me one time when I was about 8 or 9 years old. My brother and I shared a room upstairs at my dad’s place. At this house, we had a family dog who was predominantly an outdoor dog who rarely came inside and certainly was never allowed to sleep inside.

One time, at the dead of night, I woke up to hearing footsteps that sounded like my dog quickly running up the stairs. Being tired and young, I just assumed my father had let the dog inside the house. However, I could not see what it was since it was extremely dark in the room. But anyways, I pet it and it licked my hand. I then heard it run to my brother’s bedside and he woke up to pet it too. Soon after, it ran down the stairs and left.

Fast-forward to the morning, my brother and I were eating breakfast with our dad. As we all chatted, I asked dad why he let the dog in over night. He responded by saying: “I didn’t let the dog in the house and noted how the doors were all locked.” (which made sense as my dad religiously locks doors). I told him about what happened: he said it must have been a dream. My brother interjected saying: “I experienced it too.” My dad’s face dropped and he became visibly freaked out.

To this day, I have zero explanation for what occurred that night and what thing I pet. It's easily the creepiest experience I can recall.

Edit: fix