Context : The party just waded through a small army of owlbears to their main target, a Beholder that had been harassing them for weeks.
Amber (fighter) : Is my sword still covered in poo blood from stabbing the owlbear in the ass?
DM : Um… Yes?
Amber : I want to fling whatever is on the blade at the Beholder.
DM : I can understand your motivations for doing so, and I’m slightly scared to ask, but…. Why?
Amber : I want a roll to see if I can give that asshole pink eye before we kill him. Just for the extra annoyance.
In short, I allowed a dexterity check for poo flinging, and natural 1’d a constitution saving throw for the Beholder. It did, in fact, die with pink eye.