How to be less bitchy.

I wouldn't say I'm a bitch, I'm usually pretty nice but I get really bitchy and I can hear myself saying things or doing bitchy things and I don't know how to stop. It's funny sometimes how bitchy I get, because I rant and everyone finds that funny but I need to stop and I'm not sure how... anyone else ever feel this way? If you do, how do you stop it? Or do you let it out?