Hello. this might be common sense to some people here, but i feel like sharing it anyway because i had LOADS of fun with it today.
so to the point: You should get an mount that more than one can be on, like the mount for 16k, the mount from voa, mechano-hog etc. then u start yelling in dalaran if anyone wants to ride with you. when you find your victim and hes on your mount you run to kraus landing (where you can use flying mounts) and jump off dalaran. your victim will be on your mount but in the air you dissmount so he falls. best is to be a druid (i am) and u can just cast flight form, but even priests, paladins and mages can do it also. and with noggenfogger you can also use slow fall and laugh at the guy who had to pay repairs.
Step by step:
1. have an mount that can have more than 1 passenger.
2. yell in dalaran that your bored and wondering if anyone wanna ride with you (u can even ask your friends, i did xD)
3.get em to jump on your mount.
4. run to kraus landing and jump of dalaran.
5. in the air dissmount and use slowfall/bubbel/noggenfogger/flight form
6. watch your victim fall down and die and lose some repair
7. laugh at him
8. rinse and repeat for an ultimate fun and laughing evening.