Twitter is notified whenever you visit one of the more than 20 percent of sites on the web that include Twitter widgets (see http://j.mp/dcdefcon).
Turn off the flow of your data to them!
Twitter Disconnect blocks all traffic from third-party sites to Twitter servers but still lets you access Twitter itself.
Instructions: The add-on displays an icon in the location bar if a page initiates Twitter requests. You can block or unblock the requests by clicking the icon. Your preference will be remembered the next time you’re on the site.