My cousin and I were children. I'm guessing around 8, but you could probably give or take a few years. We were small enough that we slept with our heads at different ends of the bed, and we barely met in the middle. It was the mid summer, and very late at night. We both were fast asleep in bed, when suddenly I had jolted awake for whatever reason. Immediately, something felt off and the urge to look outside made me shoot up right. I looked out the window at a tree just at the edge of a forest and saw hundreds of lights. They looked like Christmas lights, but I knew they didn't have anything in a tree that big and far from the house. Then my young brain thought "fireworks!" but they never dissipated. In fact, they flicked and danced around the leaves, almost like lightning bugs, but in every color you could imagine! I was in awe. After a few moments, I woke my cousin up. She was upset with me at first, and told me to go back to sleep "you're dreaming". I refused to accept that as an answer. Until finally I pestered her enough to sit up and look. To my amazement, she saw them too! We sat there, for 15 minutes discussing what they could be and how beautiful they were. Eventually we settled on 'really cool lightning bugs or fairies' and went back to sleep. We talked about it briefly the next day and then never again. Until, in our early 20s, I looked at her and asked her if she remembered. She looked at me stunned and said "I thought I dreamed that". We both remembered ever detail the exact same, and we both had decided we imagined it, dreamed it, or remembered wrong up until that moment. I don't know what it could've been; whether it were aliens, fairies, ghosts, a cryptid, strange bugs, or even just a shared vision, it was one of the most amazing things I've ever seen and I've spent my life hoping I'd get to see it again!