You'd think this is something so basic that doesn't require explanation.
The problem is that people who require the explanation just don't get it, even after is being told.
As far as I'm concerned it totally eliminates any potential for compassion or consideration to the fact they feel horrible.
I don't remember all the time, but when I do I take along a can or two of squid on its own ink. I happen to love that stuff and most people without sea legs don't care for it. If they lack the common sense to throw-up away from people or property, they get to hurl some extra after getting a good whiff of that tasty treat.