The article webpages of The New York Times have a feature that I find particularly irritating. If I highlight some text on the webpage, it immediately pops up a question-mark (?) window offering to lookup the words for me! This supposed feature also prevents me from right-clicking the highlighted text and performing any operation on them, like copying or Google-searching them.
With this information, disabling this feature is easy if you have the Adblock Plus addon installed on Firefox. Just add the following path to Adblock:
Tried with: Adblock Plus 1.3.3 and Firefox 4.0 on Windows 7