It is poison.
It is toxic.
There is no "mercy" in sitting back sipping your post-prandial port or brandy while someone else is enjoying poison.
And it is even worse to pass him the decanter.
"I say, old boy, I wouldn't touch it, but feel free... care for a splash with that anti-freeze? Carson, would you fetch---"
"Don't be an ass....he will have a syrup of ipecac cocktail and stop being so suburban.".