[watashiato]

Relevant XKCD

https://xkcd.com/1288/ https://xkcd.com/1625/ https://xkcd.com/1679/

This is one of those things you'd better do with a userscript instead of yet another addon. Way more flexible too.

[sp332]

Or more specificaly https://xkcd.com/1838/

[enriquto]

You forgot this one: https://xkcd.com/1031/

[jshprentz]

And this one: https://xkcd.com/2304/