You're sitting in your favorite restaurant one balmy September morning.
Your waitress brings a pot of coffee and a standard 5-ounce cup.
"Would you like cream and sugar with it?" she asks.
You drink your coffee black. And hot. You decline her offer.
"Would you like arsenic with it?" she asks.
Arsenic? You're baffled. And more than a little suspicious.
"It enhances the flavor," says your waitress.
"I really don't think I want arsenic," you say, now wondering why she's so cheerful.
"It really does enhance the flavor--and there's absolutely no harm in it," she says.
"But it's arsenic!" you reply. "That's rat poison. It can kill you."
"Only in large doses," she says. "I'll add just 150 drops to your coffee. It tastes good and won't harm you," she says, still as cheery as ever.
"But 150 drops is deadly!" you reply, looking around to see if you're on "Candid Camera." You're not, and she's serious.