a few of my loves:
Helping new players and they're really appreciative of it.
Asking in town for any newb para, derv, war, etc and giving them a max gold weap and the reply with "WOOOWWWWW, THANKS DUDE!!!"
When u get that perfect Pug in Urgoz and it just works and everyone listens to the leader and you clear the area without effort in under 2 hours.
Inviting people to join my guild after helping them in a few missions and they're really chuffed about it
55ing, I just love this form of farming
Playing my SS Necro in AB and shutting down (or killing) 3 melee's at a time.
Chillblains + earth ele, self explanitory, hehehehe...
Helping guildies on missions and quests
Funny people in the game, the ones that really make you laugh...
Getting a good team in AB. I was on my Necro and got a Para, Mo and War in my group. The group gelled so well, Para was shouting like mad, monk healed me so well I once tanked 3 assassins while SS and IPing them. And the warrior was a /P and was also using awesome para buffs. We won like 10 games in a row and even waited for each other while we went to unload faction...

That wolf emote (I think it's a PvP thing) the one that makes that big orange wolf come out in front of your toon.
When my pet, Dudette, howls. OMG it's such a cool sound...
