2.) Any "bug" which afflicts masses of people living in close proximity--typically college dorms, offices, etc--with no explainable cause or origin.
3.) A "bug" which is more psychological than physical, and spreads rapidly amongst people with little to no physical contact.
2.) "The entire third floor of Palevsky Central Hall is infected with some kind of Motaba Virus or something--they've all been vomiting for two days. Wonder who started it."
3.) "Steve hasn't been in Japanese class for nearly a week but I could've sworn I saw him with his new Asian girlfriend. Must be the deadly Motaba virus."