A man walks into a bar with a friend. The man says "I'll have some H20 please," and the bartender gives him some water. The man's friend then says "I'll have H20 too, please." the bartender looks confused, and then says "one moment." he goes to the back room and grabs a special bottle. He pours and serves. After drinking it, the man's friend fell on the ground, dead. "What was that??" the bartender shrugs and says "I was just as confused when he asked for hydrogen peroxide."