Some will find this post blatantly obvious and old news, but hopefully others will find it a delightful surprise. GitHub.com parses Emoji Icon short-codes on their website to display their respective images. This works in commit messages, Markdown files, and I believe in comments (Github's Flavored Markdown).
Below is a GitHub repo I made of every single available icon as a separate file and commit message. Fork or star it for reference:
Alternatively, you also can reference this nifty
guide and cheat-sheat. The short-codes for these Emoji's are very simple. Just surround the name of the emoji with colons. For example:
git commit -m 'Fixed whatever, time for :beers:' git commit -m 'Updated README :cat2:' git commit -m 'Meow meow meow :octocat:' git commit -m ':toilet:'