As a doting father, it pains me to confess that I never heard the wolf whistles.

I saw the teenage boys, however, and knew instinctively what they were doing. Checking out my oldest daughter.

Nothing prepares you for that moment.

She and I were picking up pizza on a Friday night and as we walked past the boys I apologized to Firstborn.

This crew had a ragged, unkempt quality that seems to be the current uniform of teenage boys: Torn jeans, stretched T-shirts and a quirky obsession with blonde highlights.

That's one sorry gene pool you've got to choose from, I told Firstborn.

She laughed.

A moment later, we saw two more boys, who were just about the same age, goading each other into a fistfight on the far side of the parking lot.

Firstborn laughed again, dismissing the entire group as unworthy.

I figured this was a good sign of father-daughter communication. It wasn't like we were talking about teenage relationships — good lord, no — but learning that we shared the same dislikes set me at ease. Sort of.

To admit your daughter is old enough to be attractive to scruffy teenage boys — and that she may find them attractive as well — jolts you like a pothole on the parenting freeway.

But I didn't hear the whistles that evening.

When Firstborn figured this out, she couldn't find the words to explain her disbelief.

"You're ... you're ... you're supposed to defend my honor," she finally stammered.

How do you answer that one? Trust me, you don't even try.

Fathers, beware. The teenage years sneak up on you.

One day your daughter is a regular kid, watching cartoons on a Saturday morning, and the next day she's taping photos of tattooed punk rockers on the door to her room.

Before you realize everything has changed, you're still thinking you've got the parenting assignment under control. You figure schedules and hobbies and after-school sports will insulate her from life's misadventures. From badly behaved boys.

Then the dolls get dumped. Your daughter starts shaving her legs. All those Harry Potter books take a backseat to novels about teenage romance.

Your daughter discovers makeup and argues about skirt length. You want her to wear a nun's habit; she wants to wear something a size too small.

Being a father is hard at times like this, when you realize that things are different. You're torn in two.

As you marvel at your daughter's emerging beauty, you ache inside for the little girl who once held your hand.

Call it a wolf whistle from reality — and you'd best be around to hear it.