When I was a child, I went through a Digimon phase. One night me my brother were outside jumping on a trampoline or something and we saw some little floating lights swirling around us. There seemed to be more and more of them and I got terrified cause I thought I was getting sent to the Digimon realm or something, so he and I ran away screaming. So that was my first experience with fireflies.

The 9 o’clock tiger
https://youtu.be/1wy2pkjt_3k
I found a YouTube link in your comment. Here are links to the same video on alternative frontends that protect your privacy: