Here's one I did to a carpet cleaning company telemarketer once.
TM: Good evening (they
always call during supper), this is ------ carpet cleaners, how are you?
Me: This is amazing, how did you know to call right now?
TM: May I tell you about our specials?
Me: Never mind, just tell me if you can get blood out of my carpet.
TM: We have several methods depending on how old the stain is.
Me: It just happened.
TM: In that case we..
Me: (interuppting) It's a lot of blood.
TM: We can handle..
Me: (interupting again) How soon can you get here?
TM: (starting to sound concerned) We can...
Me: Is that sirens?
(silence)
Me: &%^$@#, drop phone on counter and start shouting "YOU'LL NEVER TAKE ME ALIVE" while pounding on door.
Opened door and lit a string of firecrackers.
They never called back
