Twitter is notified whenever you visit one of the more than 20 percent of sites on the web that include Twitter widgets. 
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.
Note about using Twitter Disconnect with other filtering add-ons like Adblock Plus: Twitter Disconnect is compatible with other filtering add-ons, but if you want Twitter Disconnect to show blocking info, uninstall then reinstall any other filtering add-ons you have (i.e., Twitter Disconnect must be added first).
1. See http://youtu.be/BK_E3Bjpe0E.