Noun. A disease characterized by excessive foaming at the mouth induced by fun dip, a tang 'stache, and extreme frostbite from fort-building in the snow. Origin relates back to a young girl from Wisconsin's best weapon in her quest to make her BFF King of Television.
"That pink foam is a clear sign of Rybies."
"SICK! That guy just wiped his Rybies all over the door handle at McDonalds."