There’s a really funny poll going on over at Fark.com.
What’s your favorite prank to pull on telemarketers?

I used to get calls all the time from the local Policeman’s Benevolent Association. It was always a man with a very stern cop-like voice.  I tried all sorts of replies, and he’d always do his best to bully me into a donation.  One time he practically threatened me.  Something along the lines of… "Ma’am, do you have a PROBLEM with police officers?  Would you like to?" That got me so angry that I looked up the association’s name on the internet and found out that the calls were likely NOT coming from actual police officers, just hired telemarketers like all the rest.  So the next time the call came I stopped the man in mid-sentence and asked "Sir, are you a police officer?" He stumbled on his words, and his hostile tone immediately wilted.  He admitted that he was not an officer, and started reading a spiel full of legalese intended for dubious folks like me.  I said "Thanks but no thanks" and hung up.

Guess it worked, ‘cuz I never heard from those guys again.  :-D

I really don’t have a problem with cops in general; they’ve never harrassed me and have always come to my aid when I needed help.  Deceitful telemarketers really bug me, but I mostly consider police to be the good guys.  I’ll never forget the time in Austin when a pervert followed me home and tried to attack me. His attempt was thwarted by my boyfriend-at-the-time, and he bolted back to his car and drove away.  But I got the guy’s license plate number and filed a police report.  Went in to the station to see if I could identify him via a photo lineup.  I didn’t pick the right guy.  But the cop took pity on me and — get this!! — actually showed me the correct picture, TOLD me the guy’s name and that he worked at a certain gas station close to my house.  I never went to that station again and that was that.  Of course the cop had made me promise I would use the info only to protect myself and not to seek vengeance before he told me the man’s info.  He trusted me, and probably broke the law by breaching the suspect’s confidentiality, but I’m forever grateful for that.  Cops like that are MY HEROES.