Now this MAY work in other cities, with other odd spots and walljumps, but this is something I found personally as a fluke, which I find really fun to do sometimes!
This screeny should explain it all. If you need more detailed instructions, then go read below screeny.
Step1. Walljump up to top of building
Step2. Put pet on 'Stay' on edge of building
Step3. Shadowmeld, Stealth, or go Invis somehow off in the back area.
(I should state, I have only tested this with Night Elf's Shadowmeld, and not Stealth. But I imagine it all works the same.)
NOW, anyone who is standing on the ground floor, and is NOT in your group, they will see your pet as "Level 70 Beast", their cursor will be the little attack 'sword', and the pet will appear red and aggro-able.
Kindve a neat trick I stumbled onto when my wife happened to see it when I was jumping around. Dont know if it can be done elsewhere, cant imagine why not if its a similar setup. Just requires a distance, and some off LoS.
If you find more spots, please post them. Otherwise, have fun tricking people into thinking horde are around lol.