You put the directory somewhere (eg. usb drive) and hope someone enters the directory and executes a git command.

To elaborate on your comment, on UNIX systems, you don't put "." in $PATH because someone might put a malicious executable named `ls` or `cd`, in a directory. It doesn't have root privileges, but it runs as your user account and can get some kind of persistence by hooking `~/.bashrc`. And perhaps by wrapping `sudo` it can eventually get root privileges.

That doesn't work if . is at the end of $PATH though? Since the real ones would take precedence due to how executable searching works...?

You never type sl on accident?