I’ve always considered myself a person with above-average intelligence.

This belief, however misconstrued, originated with the nuns who attempted to impart an education to me in the ’60s and ’70s. As ordained by the diocese, they would administer all manner of standardized tests and report to my parents:

“Your daughter’s a smart girl. She just doesn’t apply herself.” (Alternately: “Catherine isn’t working up to her full potential.”)

Once, when discussing my college options with our earnest but narcoleptic high school counselor, Sister Mary Cleophas, I accidently glimpsed my IQ score on the “permanent record” she held in her hands as she nodded off.

In 1972, this was akin to discovering your father’s pay stub or the contents of your mother’s bedside table. IQ scores were classified, top secret, “don’t ask, don’t tell” information no child was permitted to have.

Naturally, I became obsessed with the number and looked it up on the IQ scale (how I accomplished this without Google, I cannot say). There — in the Encyclopedia Britannica or other ancient tome — was my quotient, solidly above average. (Not “genius,” mind you. That DNA went to my middle sister — the lawyer — along with thin, tapered fingers and flawless skin.)

But, my score wasn’t chopped liver, and I’ve been clinging to it like a life preserver for decades.

Why?

Because, most days, I’m convinced I am the STUPIDEST PERSON IN THE WORLD!

Just the other day, for example, I spent far too long pushing on a door that was clearly marked PULL. I’m talking five, maybe 10 seconds, complete with cussing at the door for not opening readily.

Can you say, “One taco short of a combo plate”?

While cooking, I will routinely reach for the lid on a pot of boiling water, completely disregarding the four oven mitts in the drawer next to the cooktop. (Yes, I said “routinely,” thus disproving the old “once burned, twice shy” theory.)

In other words, the wheel is turning, but the hamster is dead.

On more than one occasion, I have walked full bore into a closed screened door. While these antics provided an endless visual loop of hilarity for my family, nothing makes a person feel stupider. Except maybe walking into a plate glass window.

Translation: Prairie Village must be missing its idiot.

The latest example of my stupidity occurred three weeks ago when I returned to the gym after a long, winter hiatus. My objective? To sweat away 25 pounds in four weeks, just in time for the Mediterranean cruise I won in a Food and Wine magazine Facebook contest (more on that story of stupid luck next time).

The goal, in my mind, was totally reachable. All it would take were two daily workouts at elite athlete intensity and food consumption of 800 calories per day.

In the gym, I tackled each of the weight machines with a vigorous sense of purpose. I pumped, I pulled, I lifted, I stretched.

I put extra effort into the hip adductor machine, willing my inner thighs to melt away as I thrust my legs, in and out, in and out….

Three workouts in a row and I was feeling great. Until day four.

On that day, I awoke in agony. My right thigh, hip and lower back were in searing pain. Bruises had appeared overnight on my groin area. I shuffled to the bathroom like Tim Conway’s old man character on “The Carol Burnett Show.”

The descent to the toilet seat from the upright position was beyond excruciating.

“HOW COULD I BE SO STUPID! I HAVE AN ABOVE-AVERAGE IQ!” I cried.

Despite megadoses of ibuprofen, Tylenol, Icy Hot and heat patches, the pain took weeks to subside.

Riding into Kansas City to attend my mother’s wedding, I held a bag of frozen corn to my groin under my fancy pants. (We were out of frozen peas.)

“What’d you do, Mom?” my son inquired from the back seat.

“Let’s just say I’m a few peas short of a casserole, dear,” I replied, switching the bag of corn to the tender spot on my back. “You know, like all foam and no beer?”

The moral of the story is this (Parents, please take note): IQ tests mean absolutely nothing. In the end, the brilliant Forrest Gump had the right idea: Stupid is as stupid does.