When I started using Privoxy, of course one of the first things I did was disabling animated GIFs, except on .freepascal.org, as I love that racing cheetah. Though, recently (as in the last few years) I've noticed that a lot of (meaning just about all) animated GIFs on Buzzfeed, Google+, etc. are making it through, and they seem to be getting only more and more used. I tested and removing the exception of .freepascal.org blocks that cheetah, but the annoying GIFs still make it through. I don't know enough about the image format or how to deanimate them to send a patch or anything. Sorry.
An example in a Buzzfeed article I was reading today: