The MMA Blindfold is an extension (or add-on) for Firefox which hides certain details from Wikipedia pages about MMA results. yes, I know, perhaps quite a niche target audience.
The magic "Install" button can be found at addons.mozilla.org. Or, if you prefer to verify the code yourself beforehand, you can install it manually using the following zip file.
Zip file (20 kb)
mmablindfold_0.1.zip - You can install this from the about:debugging page in Firefox.
Wikipedia pages cover many professional MMA events (from many different organisations) in great detail, including the winners and losers, win method, and the round number and time of stoppage. This is excellent information, of course, but if one doesn't want to know the result, it's difficult to see who took part in past events. In this case it could be useful to have a "blindfold" which lets you see the event details and participants, without revealing the winners and losers.
Just imagine, you know there was a big MMA event last weekend, but you can't remember who was in it. You want to decide whether it's worth watching by seeing who took part, and it would also be nice to know which bout won the "Fight of the Night" award. But, you don't want to ruin your watching enjoyment by accidentally revealing who won and how.
This extension covers that case - when activated, it removes some of the information (like win method and time) from the results tables inside the Wikipedia page. The participants in each bout are randomly swapped so you can see who competed against whom in which weight class and on which card, but not who won.
In addition, the "Fight of the Night" bonus award (if there is one) is listed but with the competitors again randomly swapped. Any "Performance of the Night" bonus information is deleted from the page.
When you're on a Wikipedia page, you get a "page icon" in the address bar which looks like this: 
(when off), or 
(when on). This button lets you activate and deactivate the blindfold, so when it's red, your blindfold is on.
When you navigate inside Wikipedia from page to page, the blindfold stays active. Also, when it's active, the left sidebar of the page turns light green to confirm that you can safely browse. Pages about future events are not affected by the blindfold, so you can easily scroll forwards and backwards without revealing any results.
On non-Wikipedia pages, the blindfold does nothing.
The Blindfold doesn't send or receive anything from the internet, it only grabs data from the current webpage as held by Firefox and modifies the content inside Firefox. Nothing is sent to the Activity Workshop, no extra requests are sent to Wikipedia (apart from the regular page requests), and nothing is stored locally (except for the cookie which specifies whether the blindfold is on or not).
The best way is just to try it out navigating to your favourite pages. Many pages about MMA events seem to work, and even some non-MMA combat sports too. If it doesn't work for you, raise an issue or send an email including the page details, and we can try to get support for those pages added too.
The source code is at Github and is available under a Mozilla Public License (MPL2).