A chemist walks into a bar. He says, "I'll have H2O." The bartender, a chemistry major at college, obliges, and pours him a glass of water. The chemist drinks the water.
The mechanic sitting next to him, not exactly the brightest guy, says, "I'll have H2O too." The bartender, still using his knowledge of chemistry, pours him a glass of hydrogen peroxide. "Your funeral," the bartender said. The mechanic drinks the hydrogen peroxide and dies on the spot.
