Prank phone calls

I'm a big fan of the prank answer.  Your phone rings, you pick it up, and "You've reached Tom. I'm sorry, I AM able to pick up the phone. At the tone please begin your message..."

They always pause for a long time before realizing they are actually on the line with someone

I like to pretend to be very hard of hearing when telemarketers call.

Make them repeat their whole spiel 4-5 times in little snippets

I had an outgoing message on my answering machine of: "Hello?.....Oh, hi.........uh-huh............yeah, well I'm not at home right now, this is my answering service. Leave a message at the beep".

Then a few weeks later, I changed the machine but for a while I answered the phone with the same script.

I also enjoy answering the phone with "What?" or "Speak." 

When I was a young officer I always wanted to work at HQMC in DC so I could answer the phone "Marine Corps, what the f%$k do you want?

One of the best phone pranks I ever pulled was calling one of my favorite restaurants on a cell phone from my car with the window down and then beat my chest rapidly while informing them that I was in a news chopper covering a police chase in which the suspects were now loose in the vicinity. My wife was driving and the prankee was a dear friend of hers who was exremely blond. We cracked up as we drove into their parking lot to find her peering out the front door looking for all the action. Terry lives in Charleston now but occassionally calls to tell me to kiss her butt.