Or why you shouldn’t attempt package manager installs before coffee.

$ brew cask search virtualbox
==> Exact match
virtualbox
==> Partial matches
virtualbox-extension-pack

$ brew cask install virtualbox-extensions-pack
Error: No available Cask for virtualbox-extensions-pack
Error: nothing to install

$ echo "HUH!?"
HUH!?

$ brew cask install virtualbox-extension-pack
==> Satisfying dependencies
==> Installing Cask dependencies: virtualbox
[..]
complete

$ cowsay -e "><"  "Mumble grumble"
 ________________ 
< mumble grumble >
 ---------------- 
        \   ^__^
         \  (><)\_______
            (__)\       )\/\
                ||----w |
                ||     ||