You’d think I’ve lived on this planet long enough to know a thing or two about human behavior. Apparently, I don’t. I’m more baffled than ever by so many things I see people do.

Last night, for instance, I saw a pregnant woman spend a good two minutes talking on the news, all the while holding both palms on her belly. I know this isn’t new. Artists as far back as the 14th century depicted the Virgin Mary with her hands planted on her blessed baby bump. I just couldn’t imagine why. So I Googled. A blogger for the Multiwear web site wrote that women palm their tummies because they want the world to know they’re pregnant. She went so far as to suggest that expectant mothers who pose for pictures with their hands by their sides are “not that excited about being pregnant.” Not that excited?! I was over the moon when I was pregnant. I just didn’t realize I had to advertise it. And if I had picked a pregnancy transformation to crow about, it would not have been my beachball-size belly; it would have been my breasts, which grew two cup sizes to an A. That’s where I should have rested my hands.

A trendier gesture that’s got me baffled comes from Facebook friends I see posing with their pinkies and thumbs extended and the other three fingers turned down. I started to wonder if I was the only idiot on Facebook who didn’t get the gesture until I learned that it’s called a shaka and means “hang loose” in Hawaiian surf culture. That made me think I might not be an idiot after all. I’m neither Hawaiian nor a surfer. Then again, neither are the friends I see flashing the shaka on Facebook. God knows why they’d want us to think they come from a state where people consume an average of 16 cans of Spam a year.

Speaking of Facebook, over the past year or so I’ve seen selfies of several runner friends biting medals they won at a race. I never thought to bite my medals. If I had, I probably wouldn’t want friends to know. I figured there had to be an explanation beyond mental illness. Google turned one up along with photos of Michael Phelps, Usain Bolt and Simone Biles biting their Olympic gold medals. Real gold is soft enough to show teeth marks from a bite. I’m sure Olympians know their medals are real. They also know their picture is more likely to make the cover of Sports Illustrated if they’re doing something that suggests they’ve got the brains of a termite. I can only hope my friends biting their plastic medals are smart enough to know their picture isn’t.

And what about all those male and female ways of doing things? Like taking off a t-shirt. Anybody with XX chromosomes will cross her arms and pull the shirt up from the bottom. Men pull from the collar. Of course, my way makes more sense. Why stretch out the collar? But I didn’t question my husband’s shirt removal any more than I questioned his stuffing keys, cell phone, tissues and lip balm into his pockets instead of a handbag. So, of course, I was taken aback a few weeks ago when he asked me to teach him to remove a shirt the womanly way. That’s when I learned there’s a practical reason men and women disrobe differently. The collar pull works fine on most men’s shirts because they’re long and loose. (The shirts, that is, not the men.) It didn’t work on the rash guard Bob wears to surf because that’s tight as the shirts women wear to catch the eye of collar pullers. Bob did learn how to remove his rash guard my way, though it took several lessons. I suppose I should find that reassuring.

The most absurd social expectation of the sexes has got to be that women walk on the inner side of a sidewalk and men walk on the street side. I remember learning decades ago, probably from my friend Karen the librarian, that this practice is rooted in the Middle Ages, when people dumped their chamber pots out the window. A gentleman was expected to walk in the line of fire. I assume he also was not to complain if his lady put a quick end to the date when he got hit.  You’d think the invention of flushing toilets in 1853 would have made such sidewalk gallantry obsolete. But not according to etiquette guru Emily Post, author of my mother’s bible. So when Bob and I go out, I walk on the inside and he walks on the street side. My mother may be 1,350 miles away in an assisted-living facility, but I know she’s watching. And if Bob and I are so gauche as to walk on the wrong sides, she’ll let us have it, quite possibly with a loaded chamber pot.