I listen to a prank call show where one of his recurring bits is to call people who listed used items for sale to let them know that he's not interested in purchasing their item.
Not sure if I can find a particular episode right now that has that type of call but if you look up Phone Losers of America, or The Snow Plow Show (both are the same guy) you can find lots of Craigslist calls.
Here's a similar idea where he pretends to be calling from AT&T to let them know they have no incoming calls: