Pennsylvania Rob asked to borrow my projector, so I was showing him how it works.

Because projectors used to cost a lot of money — and the replacement light bulbs used to cost hundreds of dollars — I can get pretty urgent and self-important on the care and proper use of the projector. It seems to be a relic of my many decades as a pretty urgent and self-important guy.

It's just that I can remember the day when I finally entered the ranks of Those Very Cool People Who Are Successful Enough To Have Their Very Own Projectors.

Anyway, I'd gone over the basics like the power cord and on-off switch.

Now, we were dealing with some very technical, very upper level, very rather rather issues.

The Keystone Effect
I asked, "Rob, do you know about

Technical Note #12: Keystoning
When projecting from a low surface, such as a conference room table, onto a higher perpendicular surface, such as a screen or white wall well above where the plane of the table intersects with the plane of the higher surface, the image is no longer a rectangle. It becomes a symmetrical trapezoid.

This is known as the keystone effect. Happily, in the contemporary day, one need only use the keystone adjustment and the computer within the projector will automatically correct the shape. (I think it is amazing and delightful.)

He looked at me quizzically, so I explained keystoning.

Immediate Relief
Rob was strangely relieved to hear my explanation of intersecting planes. He smiled as he sighed.

He explained: "When you asked me if I knew about keystoning, I thought you had — as you often do — departed from the subject at hand to ask me about something unrelated. And, frankly, I thought that keystoning sounded like some new, deviant sexual activity. And I feared that you were going to introduce me to something I might be better off not knowing."

We all know cases of that. There are so many deviant sexual activities — and so many have poetic or, increasingly now, technical names drawn from physics of geometry.

Or the culinary arts.

Here's Something I'd Rather Not Know
A recent letter to the editor in our hometown daily newspaper complained about a comment in the preceding day's issue. Though I didn't recall the offense, apparently someone had been quoted calling members of the Tea Party "tea baggers."

[SPOILER ALERT: You are about to learn about a deviant sexual practice. To avoid this, click here.]

Possibly, I'd seen that reference and just accepted it. "Tea Baggers" sounds reasonable enough a nickname. I kind of liked it. The Tea Party, like many social movements, can seem overly earnest and I find it refreshing when serious groups adopt cheerful nicknames. Though my calm makes me ill suited to the Tea Party — recent polling by The New York Times shows them to be angry — I was glad they had a cheerful nickname.

Well, the letter explained that "as everyone knows, this refers to a deviant sexual practice."

"My dear woman," I thought, glancing at the letter writer's name (and her home address, in a conservative suburb), "I do not know of this deviant sexual practice. And you clearly do. Thank you for sharing your expertise in deviant sex with our entire community."

So of course, I did my intellectual duty by Googling "tea bagger." And I learned plenty. I won't provide you with a link. You'll have to Google it yourself, you intellectual, you.

Meanwhile, Back In The Boudoir
So I told Mrs. Isaac (the wife, not the mother — and why must they share this name?) about Rob's fearful — and, I might add, slightly hopeful — misinterpretation of keystoning.

She laughed.

Now she keeps begging for keystoning. And I don't know what to do.