$ sh <(curl hashbang.sh | gpg)
Bash process substitution which curls the website 'hashbang.sh' and executes the shell script embedded in the page.
This is obviously not the most secure way to run something like this, and we will scold you if you try.
The smarter way would be:
Download locally over SSL
Verify integrity with GPG (if available):
Inspect source code: