I cannot attend that thing you are organizing due to my tendency to say true and reasonable things that make some people panic.

It's not that Christmas parties are all that terrible once the brandy hits the bloodstream. But we introverts dread these things in advance. Why can't we just stay at home and read a good book? Or even a bad one? All you need is a servicable excuse. You can change the world if you have a good enough excuse. Or an alibi.