Some things are sure to upset some readers. Two women readers called today to say they were offended by a Page One reference to St. Louis as “The Lou.”

(The skyteaser at the top of the Post-Dispatch’s front page this morning said: Grab your sombrero for Cinco de Mayo! Wondering where to party south-of-the-border style right here in the Lou? Plan your weekend with Get Out.)

The “loo,” of course, is British slang for toilet. Wikipedia says the origin of that is unknown.

I was greeted this morning by this voice message:

“Yeah, you don’t have to call me back (she didn’t leave a name or number) but I am looking at the headline today — Wondering where to party south-of-the-border style right here in the Lou? In the toilet? If St. Louis is the Lou, then Kansas City is the Can. I think it’s disgusting. And I know that stupid woman columnist started using the Lou for St. Louis. I’d like to wring her neck. “

The caller’s message took a more disturbing turn:

“And I don’t care about the Cinco de Mayo and all their Mexican food and Mexican celebrations and Mexican languages. Because Spanish it ain’t. Sorry. Bye.”

Another caller, who identified herself as a long-time reader, left her name and number and we spoke about using the Lou. She seemed quite rational — and deeply offended.

She said she stopped reading columnist Deb Peterson some time ago because of her frequent use of the Lou. The woman said she finds it offensive to use the Lou on the front page because the word means toilet.

I noted that the British use has a different spelling. Nonetheless, she said, she was offended and tempted to cancel her subscription.

So why use it if we know some readers are going to be offended? My own take is that we wouldn’t use “Lou” in a real headline, because it is slang — and slang rarely has a place in a front-page headline. But it’s fine in a promotional teaser that sends readers to info on Cinco de Mayo, a day designed for drinking and partying.

This topic last came up in the Editor’s Desk in January, when “the Lou” also appeared in a skyteaser to the Get Out section. Several commented then that they and their friends frequently refer to St. Louis as the Lou. One person who says he commonly uses the term is the page designer who did today’s front page — and wrote the teaser.