help with telling the boys no

i guess im on a roll now :P so at my church and school there are multiple guys that i see as just friends however they apparently think i flirt with them and loudly tell everyone that i flirt too much. this is embarassing and also not true! i like to talk, a lot! and just because a girl gives you the time of day doesn't mean she is swooning for you! ugh frustrated!!! anyway now i have a reputation that i am a flirt and i have recently found out this rumor has filtered back to some parents and now some of my friends are not being allowed to hang out with me! i refuse to just never talk to a boy, i have found that many times guys can be better friends than girls. anyway any advice on how to stop these rumors without becoming a nun would be helpful!