1)Rhodes' Gas or Brown's Gas (William A Rhodes and Professor Yull Brown)
2)the gas produced after the electrolysis of water (Hydrogen + Hydrogen + Oxygen)
3)Since it contains Hydrogen, it is 3 times more potent than gasoline
4)This is NOT a slang term for Water and is NOT Water Vapor
5)it can be made in any home easily with the proper materials
HHO's Most common reference would be as an additive to a fuel mixture, causing a more explosive mixture with less gasoline, thereby increasing gas mileage.