For Debian 8.0 run the following as root:

echo 'deb http://download.opensuse.org/repositories/home:/Head_on_a_Stick:/obmenu-generator/Debian_8.0/ /' > /etc/apt/sources.list.d/obmenu-generator.list 
apt-get update
apt-get install obmenu-generator

You can add the repository key to apt. Keep in mind that the owner of the key may distribute updates, packages and repositories that your system will trust (more information). To add the key, run:

wget -nv https://download.opensuse.org/repositories/home:Head_on_a_Stick:obmenu-generator/Debian_8.0/Release.key -O Release.key
apt-key add - < Release.key
apt-get update