Guake is a top-down terminal for Gnome (in the style of Yakuake for KDE, Tilda or the terminal used in Quake).
Running Guake Terminal from the launcher.
Running Guake using F12.
Using Guake preferences to customize your experience.
To install Guake Terminal just run the following commands via your systems Terminal.
sudo apt-get install guake
That's it please enjoy your new Software.