Hmmm, surely here it could go in either location because it could be fool singularly, or fools plural…April Fools' Day lasts forever on the internet
...and I've had to look up a punctuation guide to the apostrophe. Apparently the apostrophe can come before or after the S so long as one is consistent in writing a passage; of course the internet could just be fooling me.
Or apparently understand the subtlety of the word play on unusual collective nouns, in the way that @simon ess doesNo matter how hard you try, your'll never beat a crow on the Orient express.