| I don't know if this bird tweets or clucks or warbles. |
And probably, no one is spreading nasty rumors about you. (But I'll admit, these are all guesses.)
If you don't know what I'm writing about, then you probably don't do much on Twitter. Because if you're like me, and are (somewhat) active on Twitter, then you probably see the above messages maybe once a day.
It works like this, as far as I can tell (and I'm no expert): There's some kind of hack where you get a direct message from one of your followers saying that "someone is spreading bad rumors about you" (or whatever) and there's a link to click. Click that link and... well, I don't know because I've never clicked the link, but I assume it somehow leads down the path that everyone who follows you gets the same spam message.
OK, I just Google'd it. This guy is an expert on it, and he does a better job of describing it here: http://www.hyphenet.com/blog/2012/05/07/dont-let-the-bad-rumors-dm-phishing-scam-hijack-your-twitter-account/