Mine is....without a shadow of a douth.......the first I killed a human with a Burst fire from a submachine gun with the Bloddy Mess trait..........I freaking love that!

PS: Dont use Bloddy Mess in Fallout 3 its not worth it

So whats yours?

Killing Lynette, Vault Cities First Citizen is ALWAYS very satisfying.

Delivering the Water Chip back to the Overseer with a dumb character.

Retartd characthers are always fun

being a pro boxer, becoming a pormstar

blowing up stuff with nuclear effect :D well i think that sums it up

Gaining the "Divorced" karma trait, after shooting the shotgun wedding wife in the head.

As I have found a whale and a flower pot. Muste read the book again. 42

Almost every random encounter and easter egg was fantastic and the extra unlockable special perks were great.

It was simply a good story with a bunch of ingame stuff to explore and collect. That maked the whole game to one of my favorite memories ^^

I think it would have to be the first time a stray round killed a child

..... and then turning that kill count into a sport

For me, there are quite a few. The top three would be:

1. Masters destruction

2. "Yes, you can touch things."

3. Encounters with Harold troughout the Fallout series.

Harold in Fallouts 1, 2, AND 3...
Moo, I say!
The End of the Overseer in Fallout 1.

YOU DARE EXILE ME?!?!?! Bwahaha! *cough*
Well, Time to leave.

Fist pumping for like 20 minutes straight after blowing a huge hole in Gizmo's chest during my first ever playthrough of Fallout 1.

Then reloading my save and doing it again.

And again.

And again. Maybe you'll sit and sigh, wishing that I were near
Then maybe you'll ask me to come back again
And maybe I'll say "Maybe"

This shotgun wedding was definitely my most memorable, and of course the subsequent divorce. Returning to the father afterwards and telling him his son was dead was also very satisfying.
I'm pretty sure I was playing a female character and had already slept with the daughter but got caught sleeping with Davin (it gets lonely in the wastes). It was fun having Davin follow you for a short while just because of the way he ran....only for a short while though, his general incompetence with any sort of weapon deserved punishment.
This is the one moment I tell others about to try and get them to play FO2. They usually just think I'm a bit sick.

Playing a character with 1 in luck and 10 in charisma. I sure did catch a lot of STDs in New Reno.

nailing stickys head to a wall with a railway rifle , never fails to ammuse EAGLES MAY FLY HIGH, BUT WEASLES DONT GET svckED INTO JET ENGINES

looking at the cardboard box of fallout 1 and turning it over to look at the back. this has to be good i thought.

My first thought when looking at the box was, I kid you not, "Why does that guy have a vacuum cleaner on his head?" I was about 12 at the time Maybe you'll sit and sigh, wishing that I were near
Then maybe you'll ask me to come back again
And maybe I'll say "Maybe"

Easy one:

"War, war never changes." Great Ron Perlman's performance.

And trying to get my mouse to work while the overseer walks back to the vault after casting me out (really wanted to kill that bastard), and then seeing him explode as my char killed him without me doing anything.
Epic.

My favorite would have to be playing FO2 with a corrupted disk so that all the characters sounded like little girls. Yes, very little girls!

Fallout 3 - The first time I saw a head explode. I'll be honest, I didn't know anything about the gameplay mechanics for FO3 when I picked it up, and that Raider's jaw going flying across my screen will forever be imprinted in my memory.

when i first loaded up my realism mod i took a sniper and sniped Enclave from a far and then watching the others continue to sit there like nothing happened... I had a lot of fun that day... Still use that realism mod.

I think I was in new reno, and some sorta fight broke out between me and my followers and one of the families. All was going well till turn 7 or so, we were fighting in the middle of town when one of my guys runs outta bullets for his weapon. Not thinking about how I had just pulled off all shotgun shells for my other minion I see him put the gun away and pull out a rocket launcher. He then pumps himself up on jet and fires a rocket at the enemy he was shooting.

..... and promptly misses.

The rocket goes and nails a door guard on the opposite faction which brings them into the fight against us. This wasn't too bad, I didn't like them anyway. Then next turn another mininon brought down his target so he switches to another and promptly misses there too. Nailing the 3rd family guard AND one of the poor people in the town!!!

......

So now the ENTIRE town is fighting, shots going everywhere and all kinds of mayhem. It was then that I saw some of the drug dealers getting hit by stray bullets and bringing the fighting to literally EVERYONE in town outside of some shop keepers.

Some of the funny memories from that fight include watching a drug dealer fighting a casino guard, BOTH getting blown to bits by my rocket launching minion and the poor of the city going up to both bodies and grabbing their guns to launch into attacks against everyone and anyone.

The fight probably took 3 hours and wiped out everyone on that screen that was involved, including one of my own minions. But it was such a fun fight and took so long, with so much death and destruction that I couldn't load a save and just continued on. It took me a few more hours to clear the last casinos of the 2 or 3 people that weren't involved in the fighting but only the family that didn't have a compound on that screen 'won' that fight and I packed my car with every gun and coin I could. Sold everything else to the shop keepers, and anyone that would take it and had a massive stash of drugs and ammo to boot.

Game kinda went to easy mode after that, with so much equipment and caps. But it's a fight I'll never forget