A friend told me that if you use undesirable language (please don't stoop to racial slurs), they'll mark your number as 'hostile'. This will propagate to other lists, removing you from them before you're even added. She swears (pun intended) by it.
Edit: it's important you don't threaten them, lest you be added to a different kind of list...
If it's a non-racial cuss, she's sent it to these folks. One bloke had the audacity to ask her to stop using that type of language... so she used it even harder.