Only yesterday, I was pretty smart.

Yep, I had managed to get a college degree and a fairly respectable job, plus I could figure out the correct answers on “Wheel of Fortune” before Vanna turned over the last letter.

I even knew not to use the blow dryer while in the bathtub or date middle-aged men who still live with their mothers.

I felt I had a lot of wisdom to impart to my daughter, like: “Never let a man see you put on control top pantyhose” (or, for that matter, take them off. Someone could get hurt).

And for many years, I was smart enough to know the correct answers to Shannon’s every question, at least as far as she knew.

But on one recent day, not long before Shannon’s 15th birthday, I awoke stupid. I suddenly was an idiot, a dunce, superdork, someone about as sharp as a buttermilk biscuit.

Not only am I too dense to know good music when it vibrates my car and the houses on both sides of the road, I am too slow to understand why Shannon can’t possibly clean her room and still have time to apply makeup and fix her hair before Alli’s party, and too dense to know why her 11:30 p.m. curfew makes her appear childish among her friends.

It seems I get dumber the older Shannon gets and, this will astonish you, my IQ drops exponentially when I am in the presence of more than one teen.

Whenever Shannon has a friend around there is so much eye rolling that I expect at any moment to see one of ’em pop out and roll across the floor.

Suddenly, every comment I make is so, like, totally juvenile.

Really, I’m beginning to think I don’t deserve to drive her around and buy her stuff.

Just the other day, I turned down the volume on the car radio — a song I “don’t get” because the lyrics rhyme “low” with “more” and talk a lot about “lady lumps” — to tell Shannon and Alli something I’d seen on TV that morning, an item about Fergie (see, I’m not too stupid to recognize a Black-Eyed Pea when I see one).

Shannon’s response to my timely and newsworthy commentary?

A bored: “Well, that was five minutes I’ll never get back.”

She was joking.