On the whole they ain't too bright. I used to just tell them to f**& off but I've taken to messing with them now.Haha, you'd think the telemarketer would detect the sarcasm in that answer.
Last one was asking if I wanted to go to a property investment seminar. I listened to most of her spiel and at the end replied, "Just one question, what's property?" She explains and I respond, "Ahh, yeah that sounds good. . . Uuummm, what's investment?"
This continues for a good 10 minutes before she hangs up on me.
My other current favourites are just saying yes to everything they say and after they introduce themselves reply with, "Aahh, f**k. You mean I stopped masturbating for this?"