I know it's wrong and I will go to hell for it, but when I get a spyware plant Microsoft support call I usually try to play dumb for as long as possible to keep the guy tied up (I'm kind of paying it forward to someone down the list who may not get called because I kept the guy going).
Once i get bored with that or they get irritated with me and it's obvious the caller is from South Asia, I start to get insulting. Some guys won't just hang up on you, they try to bully you and that's when I get really cruel and drag out truly offensive insults -- "So I hear you upgraded your residence recently, you moved from a cardboard box to a tin shanty. How's that working out? Are you still eating insects or have you moved to a fresh rat diet? Your wife, has she freshened her dot lately, or is it the same old faded one she's had for a while?"
If I get that far, the guy is usually really wound up and spewing profanity as fast as he can mentally translate it. One guy threatened to kill me and I told him that the CIA would be interested to know that he's probably a terrorist and might want to watch those drone stike videos on YouTube for a preview.
I know, it's awful, the worst kind of Americanism possible, but I figure these people are the scum of the Earth and deserve no quarter.