Speaking of telemarketers... There is a comedian named Tom Mabe in Louisville, KY, who takes their calls and messes with them. I've heard a few clips over the years and enjoyed them. Here's his website, or do a search and you may find some hits on radio stations, youtube, etc.
Corporate Comedian | Clean Comedian | Prankster | Tom Mabe
Been a while, but one I recall was from a carpet cleaning company, he asked if their service will get blood out, A LOT OF BLOOD.
His site also has a CD with clips from when he crashed a telemarketing convention and started calling their rooms at 3 AM to sell them stuff.
You get the idea, revenge on the telemarketers.