fauxliday = faux + holiday -- a fake holiday
@CopyCurmudgeon today tweeted this:
"April Fools' Day: One of my least favorite fauxlidays. But at least it taught me that @APStylebook has an entry for Aqua-Lung. For reals."
In Great Britain, holiday not describes a day of special significance and observance, but also what Americans call a vacation. When a Brit isn't at work when he normally should be, he is likely "on holiday."
The American "translation" of that sort of fauxliday is a fakecation.