My two oldest granddaughters graduated from high school Thursday. Hallie from Herriman High School and Bailie from Copper Hills High School.

It’s the biggest day in their young lives. So far. It’s the end of a long road they thought they would never reach. Now freedom is just a walk across a stage.

Me, I’m still reeling from their births 18 years ago. It seems a matter of months since Hallie was crawling around on my office floor looking for spare change to swallow. When Bailie got a boyfriend, I didn’t even know she’d gone through puberty yet.

The good news is that being capable young women, they rarely came to me for the sage advice expected from a family elder. You can thank their grandmother for that.

I can’t blame them. Not only can I still hear a little, but my wife also feels no obligation to whisper when she’s talking about me.

“Go look at all his scars again,” she told them. “Then ask yourself if you really want advice from someone who can’t tell the difference between ‘close’ and ‘way too close’ to the edge of a cliff.”

Warnings like this never stop me from dispensing advice. I’m their grandfather. It’s my job. When Bailie got her first serious boyfriend, I sought her out and counseled her to tell me if he ever hurt her feelings. She wanted to know why?

“Because whatever he does to your heart, I’ll do to his face.”

Bailie’s father is actually better equipped for this sort of thing now that I’m officially old, but my son-in-law needs to stay employed and out of jail. Me, I’m expendable. It’s a major perk in outliving one’s real usefulness.

Other advice I gave my oldest granddaughters was more practical — buckle up, don’t walk to your car alone at night, if ever offered drugs, bring them to me so I can try them first to make sure they’re safe, and always come to me if you need quick cash.

Oh, and this: Never entirely believe something a boy tells you unless you’re wearing a ring, he doesn’t have a police record, and he’s had the same job for at least a year.

Finally — and most important — become involved only with boys who are afraid of you. By this, I don’t mean boys who worry that you’ll beat them with a kitchen implement when they’re asleep, but rather boys who are terrified that they won’t live up to be the man you deserve and need them to be.

There are, admittedly, a lot of loopholes in this relationship advice. Some of the best husbands I know have a sketchy job history and been in legal trouble before. But it’s all about playing the odds.

Do not leave high school thinking the way I did in June 1971 — that you’re free. You’re not. The tough part is just beginning. A lot of work, pain and fear still await.

But if you do it right — and even if you make some stupid mistakes — it can still be worth it. It was for me.

Seriously, proof that I got at least the important parts right (eventually) walked across that stage Thursday.

Robert Kirby is The Salt Lake Tribune’s humor columnist. Follow Kirby on Facebook.