You should should change the thread title, because a meal includes the food, location, company, situation, etc.
But for strictly memorable food, I'd have to go with:
1. First time I had green curry chicken. My parents lived in Singapore while I was in college, and my first trip to visit we had dinner at a neighbor's house on like night 2. The neighbor's live-in housekeeper was Thai. And a fantastic cook.
2. Speaking of Singapore, the Murtabak from Zam Zam. Actually Singapore has a few that belong on this list--Fish head curry, pepper crab
3. First Peking Duck experience. In Beijing, at a place known for Peking Duck and heavily frequented by locals. Jesus that was good.
4. There used to be a place in downtown Munich in the most touristy part of town--I think it was called Valentin's or something like that. Anyway, it was never crowded and whenever I went there were usually only a couple of tables were occupied. The schnitzel they served had a layer of mustard between the meat and the breading. I have no idea how they did it, but it took the schnitzel to 11. Never understood why it wasn't more crowded.
5. Beef fajitas at Amalia's on Hwy 6 in NW Houston. It's closed now, but we ate there about 2-3 Fridays per month when i was growing up. I've never had better fajitas.