Sometimes you make a git commit, but there's a typo or syntax error in there by accident. I normally use
git rebase -i HEAD~2 and then through the magic of vim I'm fairly productive at squashing the two commits together.
But wouldn't it be nice if there was a way to run one command to squash your most recent commit (which probably has a useless message like "typo" anyway) into the next most recent? Lucky for you, there is now!