If they say they're John Doe from XYZ Company, ask them to spell their name. Then ask them to spell the company name. Then ask them where it is located, how long it has been in business, how many people work there, how they got into this line of work, if they are married, how many kids they have, etc. Continue asking them personal questions or questions about their company for as long as necessary.
Say "no" over and over. Be sure to vary the sound of each one, and keep a rhythmic tempo, even as they are trying to speak. This is most fun if you can do it until they hang up.
If MCI calls trying to get you to sign up for the Family and Friends Plan, reply, in as sinister a voice as you can, "I don't have any friends, would you be my friend?"
If they start out with, "How are you today?" say, "I'm so glad you asked, because no one these days seems to care, and I have all these problems. My arthritis is acting up, my eyelashes are sore, my dog has the gout..."
If the company cleans rugs, respond: "Can you get out blood? Can you get out goat blood? How about human blood?"
Tell the telemarketer you are busy at the moment and ask him/her if he/she will give you his/her home phone number so you can call him/her back. When the telemarketer explains that telemarketers cannot give out their home numbers say, "I guess you don't want anyone bothering you at home, right?" The telemarketer will agree and you say, "Me either!" Hang up.
Ask them to repeat everything they say several times.
Insist that the caller is really your buddy Leon, playing a joke. "Come on, Leon, cut it out! Seriously, Leon, how's your momma?"
Tell them you are hard of hearing and that they need to speak up . . . louder . . . louder . . .
When the salesperson asks, "Is this the homeowner?" say, "Is this the salesperson?" And when they say, "Yes," hang up.