Two men walk into a bar.
The first man says "I'd like a glass of H2O please."
So the bartender pours him a glass of water and hands it to him.
The second man asks the bartender "May I a glass of H2O, too?"
The bartender also pours him a glass of water, because he knew what he meant and had no conceivable reason to be offering or serving hydrogen peroxide (H202), much less to even have it in a bar. It would have been highly irresponsible. Thank God this bartender knew about chemistry and what the second man meant or he may have found himself charged with manslaughter, or worse - murder.