I love it!
I must admit that when I been sufficiently bored, I've had some amusement with cold callers. I start by pretending to be really enthusiatic and would say "Thats really interesting ... I think my wife would like to speak to you about that ... just give me two seconds and I'll get her...". I then leave the phone off the hook and go back to watching TV or marking homework or whatever I was doing! Mean and nasty I know.
Incidently, if you are bothered about cold-callers, being ex-directory definitely helps. What does bother me about these people is when they deliberately target old people. My grandad, who is 87, has been conned into buying things over the telephone several times before.
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