For my entire adult life, I’ve been told by other people that I don’t need to use a comma to separate the final two items in a series, providing they are connected with “and” or “or.”
Take, for example, this sentence:
I made the sandwich using jelly, peanut butter, and marshmallow.
Lots of people nowadays would say that you don’t need a comma after peanut butter. I would argue that this incorrectly implies you are using jelly and a concoction of peanut butter and marshmallow (swirled together) on your sandwich.
Diana Hacker discusses this very debate on her Rules for Writers website.
However, thanks to the wonders of social media, today I saw the best illustration of my point that I’ve ever encountered on thegloss.com. In this case, omitting the comma creates an even worse misunderstanding than just lumping the final two items together!
I also learned that my favorite kind of comma (as described above) is called an Oxford comma. You learn something new every day! Not even Hacker told me that.
So next time you’re tempted to cave to pressure and omit the final comma in a series, you can stop and think about Hacker, strippers, and JFK and Stalin (whoops!). Just say no to unintended pairings!