When the Scourge Invasion first took place (Patch 1.12) The Argent Dawn NPCs in all the capitals were accompanied by this horse. It was a rather low level and had an almost instant respawn timer. Setting your status with the Argent Dawn to ""At War"" allowed you to repeatedly and mercilessly slaughter the poor creature. Blizzard removed the NPC due to the actions of immature individuals like myself who would kite the horse into the AH, where it would make a lot of noise.

Another trick was to invite someone to party with you, and then kill the horse, hurting their reputation. Cruel, especially back in the day when AD rep was worth something, and I never did it personally, but I did witness it happen.