Yes. I did. I only play on PvE servers, but I have to say that this guy deserved it.
His name: no clue, started with a "G", Dwarf hunter, level 36ish
It started out early in the day, husband and I were playing our level 25 Blood Elf Paladins. We were finishing up some quests in Silverpine Forest and were heading to the Greymane Wall to get that guy's hand. We see Son of Arugal and decide to extract some revenge on him. About halfway through, while we are using the AoE Consecrate because I hadalso aggroed a worg in the area, both Arugal and the wolf die quickly as I THINK another wolf has run in. Turns out the "new" wolf had the name "Shadow" and I thought "that's not right?!" Well, yeah, it was this flagged numbnut Dwarf who must have thought either he'd flag us by running through our Consecrate or that we would accidently attack his flagged wolf and then he could kill 2 lowbies without them knowing what hit them.
I HATE JERKS LIKE THIS!!! (insert extremely mad face here)
It just so happens that a few hours later I am running around the Barrens on my level 60 Death Knight looking for copper and tin mines. I see the call on Local Defense that "Southern Gold Road is under attack!" Since I am near there, I thought I'd take a peek at who it was that killed poor Gann. And I get to him just before he gets to the Great Lift. And guess who? Yep, that same little Dwarf. He had been ?? to our Paladins, but I now see he is only level 36. I stop my DK in front of him before he gets to the Lift and give him a "/no" but this little sh*t goes right past me and sends his wolf on the first Horde guard at the Lift. And so I couldn't help myself-I ran over and with a couple of strokes he was dead. YOU DON'T ATTACK MY NPCs THAT YOU DON"T NEED TO!
Sidenote: I have taken at least 5 Alliance characters through this area. It is pretty much the only way to get to the flight path that Alliance have in western Thousand Needles. And NOT ONCE did I have to kill those guards! In fact, in four years of playing I have never killed a opposing factions NPC. Never.
Yeah, I'm a coward. I didn't know if this guy had a rogue running with him(most people don't run around flagged on PvE servers for no reason). So since I was now flagged I took off into the instance portal of RFK, which is pretty close. It automatically un-flags you. I came right back out only to find that poor guard at the Lift was now dead. So I took the Lift down into Thousand Needles. Me: Death Knight with the Unholy talent of "On a Pale Horse" vs a level 30 mount. Yeah, I caught up to him pretty quick. Death Grip, Icy Touch, Chains of Ice and another death for this SCHMO! I didn't stick around this time. I was sick to my stomach over this but I was PMSing and PISSED that people have NO REGARDS for other players and NO HONOR!
If it hadn't been the same JERK from the morning, I probably would have let him be, but he pushed a button and I was able to get some revenge on an IDIOT. It felt like Karma did its job. And I hated myself for having to teach some numbnut a lesson(not that it did, I'm sure he doesn't give a flying CRAP about anyone but HIMSELF). It just goes to prove the reason why I prefer to solo that to associate with what seems to me to be MOST of the wads that play this game.