wmctrl -r :ACTIVE: -b toggle,fullscreen

$ gnome-terminal --maximize

$ gnome-terminal --help
$ gnome-terminal --help-window-options

cat /usr/share/applications/gnome-terminal.desktop|sed 's/gnome-terminal/gnome-terminal --maximize/;s/Name=Terminal/& Maximized/' > ~/Desktop/gnome-terminal-maximized.desktop

#Increases the terminal size to bigger than the screen.
xdotool windowsize $(xdotool getactivewindow) 100% 100%;

#Toggle fullscreen.. twice:
wmctrl -r :ACTIVE: -b toggle,fullscreen;
wmctrl -r :ACTIVE: -b toggle,fullscreen;