Patrik, if you want, I can throw you my lesson plan on Irony. It includes an interactive game and art! Hooray!
That would actually be awesome, even just to help build ideas from. And who doesn't love games~? Want me to PM you an email?
I think high school students would greatly benefit from a class that taught tact/diplomacy. It could be a short topic on how to convey yourself accurately for the tArget listener for maximum efficiency.
Can start with how English differs from most languages and how key phrases and speaking tools in English can open the listener up to higher receptivity and more effective conveyance. How to convey neutrality without condescension etc plus how to avoid and/or utilize passive speaking like "a mistake was made" instead of "I made a mistake" in the right situations
Essentially you are giving them the tools to make their lives easier and to help them overcome unintentional miscommunication.
This actually sounds pretty interesting, especially considering my Japanese minor reflects this well with the different cultural and linguistic nuances that can easily spur miscommunication. Although, it may be a topic for another time cause... I have one day to prepare this... professors driving me insane.