Sometimes you've made mistakes and you have to triage 700 GitHub issues and Pull Requests. A lot of them will need the same answer, and your wrists will start hurting from all the switch-to-edit-copy-pasting. This extension helps with that.

Install it from the Chrome Web Store

Install it from the Firefox Add-on Store

The extension adds a little button inside GitHub's comment editing view, that allows you to choose one of the existing canned responses, and insert it in the current comment. It looks like this, and it works on both Issues and PRs pages (but at the moment not the files view of a PR):

The extension comes with a few default canned responses, but you can edit them and add your own! In the dropdown, press the edit link, and you'll get something like this: