Well, I'm sure you've all experienced it, you've annyoed someone for some reason and out of spite they've started following you and gone AFK. So, what to do? This tips post is a list of funny things to do to them
1) Find a tall area, for this example Temple of the Moon upper balcony in Darnassus (not tall but easy to use) basically, you lead your follower up stairs, and start walking around the very edge. You then find where the edge turns, and walk round the corner and keep going. The follower will try to catch up and take a nasty drop. Ow.
2) If your victim is a lower level than you, simply lead them into somewhere full of monsters that will easily kill them, and let them get aggro and die.
I'll add more later, thanks for reading.
3) Thanks to Fishy80 for this one:
As a warlock simply swim underwater and put on unending breath. They will die whereas you won't. Also, i'm not sure if this will work but if you just swim underwater, then swim straight back up to the surface, they might stay underwater and drow, therefore meaning this is available for all classes. Please tell me if this works or doesn't.