Do you mean laudanum? I heard from Lau that it's a very useful way to eliminate opponents in the Imperial Court. Hard to implicate anyone when they may have just poisoned themselves.
[Tuck under, weave over, twirl twirl bow. Okay, so maybe he gets the order and flip of some of that wrong, but hey! He's distracted by this fascinating subject okay, and the stitch is still tied all right, just inverted. It'll hold.]
I doubt that's useful on someone who isn't a guest. What if they're immediate attackers?