I would love this block to go die in a server fire.
javascript:void(document.oncontextmenu=document.onMouseDown=()=>true)
...which works for, maybe, 60% of cases. Or you can try a more sophisticated one for greater success. e.g.: javascript:(function(w){
var arr = ['contextmenu','copy','cut','paste'];
for(var i = 0, x; x = arr[i]; i++){
if(w['on' + x])w['on' + x] = null;
w.addEventListener(x, function(e){e.stopPropagation()}, true);
};
for(var j = 0, f; f = w.frames[j]; j++){try{arguments.callee(f)}catch(e){}}})(window);
Unfortunately, these don't work on 100% of the pages. Otherwise, as someone else has suggested, Firefox allows you to disable context menu hijacking for every site.
Same for sites that override ctrl + left click (to open link in new tab - some sites will treat it like you simply clicked the link and open it in the same tab - super annoying).
Above comes with disclaimer, I personally don't allow any extensions in browser I use for banking. A little bit paranoid but I prefer to reduce plain of attack when accessing my bank (of course there are other threats that may bring more severe risk, remove them one at a time :) ).
For ins.tance you can shift right click a video to use picture in picture on Youtube
You can try, but you can't. The only people you'll stop are non-tech users, and the others will shame your business for playing this game.
If you need an analogy, think of it as trying to disable screenshots in an environment where users carry a camera in the other hand...
Don't have an exemple of when it would have failed :-)