Got the idea for this from that one 4chan post I see shared on occasion where an anon says they have this very specific memory of being a kid and thinking "I will remember this moment" while standing near a couch and to this day said anon still has said memory.
Anyway one for me has a very specific song and location associated with it but I'm not really certain why. I remember going to a water park in the summer of 2005 with my dad and while we waited for the park to open I remember the park speakers near the entrance playing "Sugar We're Going Down" by Fall Out Boy. Maybe I remember it so well because this was a period in my life with I was really big into pop/punk influenced emo like early FOB and My Chemical Romance, though why this song always takes me back to that one day at a water park in 2005 is something I'm not entirely certain of.
Another song related one is I have a really specific memory of the trance song "Take Me Away" by 4Strings playing during certain "coming up next" bumpers on Nickelodeon before they would play an episode of Jimmy Neutron in the mid 00s. I think the combination of song and show was such an odd combo it just always stuck with me, and I remember for a while in the early years of YouTube always trying to find a good quality version of that song to listen to as I've always had a liking for vocal trance.
Finally, for some reason one dream from my childhood that's somehow still locked into my memory is one from when I was about 9 or 10 years old, with said dream involving me being a guest at a ball at the palace on the moon in the anime Sailor Moon. I know I was big into Sailor Moon at the time so that explains why I had the dream in the first place, but why this one dream specifically stays with me nearly 20 years later is something I'm (say it with me now) not certain of.