I've had two this week! One about credit card interest and one about student loans. Both times they cussed me out because I led them on. Suckers with accents!
I asked the fake IRS dude last week how much to fuck his mother. He didn't think that was as funny as I did.
I recently had one that told me to respond to stop a financial action against me. There was no mention of which agency but bullshit like that really poises me off. If it's real, it's sent certified or in an official IRS mail notice including a page for dispute. I reported it to the Feds.
Next time reply in their accent and ask them to meet you in an alley where you could pummel their lice infested heads.
I usually try to waste their time. That way while they're busy dealing with me they can't be molesting someone else nor can they be stealing any money for their pockets. I usually feign some sort of excited interest such as "OMG, REALLY? I'D BETTER DO SOMETHING QUICK! CAN YOU HELP ME?" I then pretend that something in the kitchen has caught fire and ask them if they can please hang on. Then I set the phone down and get on with whatever else I was doing before I was so rudely interrupted. I've also tried feigning some Asian accent and repeatedly say "Me no speak a much English" in my thickest accent. I've also told them I had their number and was reporting them to the police. Yeah, anything to harass those assholes.