Other names are apparently "Oxford Comma" or "Harvard Comma," which sound significantly less menacing than...
When you finish your essay on the romantic elements in Wordsworth's poetry...
When you proof-read too many times for a grammatical error to somehow slip through your keen eye...
When you exasperatedly figure out that you did NOT have literature class this morning and are grudgingly sitting in the basement of the JFSB and are wondering what classroom the friends you walked here with might be in and you have nothing else to do so you read your essay again and suddenly you find such errors in your essay and of course you have plenty of time to fix it but it turns out you have no means to print it--
IT GETS YOU.
P.S. Yes, that last sentence was supposed to look like that. Thanks for catching it.