Never answer questions that require a Yes answer, You have no clue what they may do with this recorded. Always ask them a question back such as who wants to know?
Do a search on call blocking devices and phones.If its a cell phone, there are free call blocking apps out there including trac & straight talk.
http://800notes.com/forum/ta-5d4e343675a5629/call-blocking-devices
I've never thought of that but that could be pretty funny to do with survey calls or ones that ask questions. I'm sure they'd love snotty receivers that'd ask them what's it to them to everything they ask. What's it to you who I vote for or how I feel. I'd think that'd be a way to leave them struggling for what to say.