
One of the scurrilous techniques I have recently developed is the Ju Ju mug.
It works like this.
1. Get an image of the person who you expect to have a disagreement with.
2. Photoshop the image until it is highly insulting, but distorted to such a degree that no-one could be absolutely certain that the image is intended to be a depiction of the target person (see an actual example of my handiwork adjacent).
3. Have the image copied onto a coffee cup.
4. Invite your interlocutor for coffee, and drink from the cup while engaged in discussion.
5. His or her gaze will constantly and inexorably drift to the cup, he or she will frequently lose the thread of the argument (through distraction) and you can move in for the kill.
Ju Ju: charm or fetish... supernatural power attributed to a charm (OED)