Yeah..that used to happen to me alot, but um..Usually when a rumor like that was started towards me, I did, infact insult that certain person >_>
The eventually, when that little messanger kid (You know that kid who's always prancing around, and knows everything that is going on in school, who is almost always unquestionably gay) Came up to me, and delivered the news that "Alex doesn't want to hang out with you anymore, and called Chelsea a (Name which I will not use online)
Well, as it turns out, I talked to him about it, and Alex never said that about me. so um..well, the next day when both went up to that other kid and..yeah...You know how it goes from here >_>
xD What you need to do is FIND THE SOURCE!!!!
Then stomp their ass. It worked for me =/