When teenage boys do it, fathers clear their throats, offer some official-sounding words about safety, and with suppressed grins and knowing glances, reach for silent pats-on-the-back.
When girls do it, or become old enough to do it, or dress like they might do it, dad is predictably in the shed, polishing his shotgun and waiting to get the young punk who dares lay a hand on his little girl.
It's a tired paradigm, and it doesn't stop either Jimmy or Sally from sneaking into that shed later on.
That's why Ferrett Steinmetz's recent open letter to his daughter is an interesting and welcome offering for those navigating the perilous realm of raising an adolescent.
Steinmetz questions the assumptions that lie beneath the gruff, hackneyed stereotypes: that she is private property to be protected and that sex is "awful when other people do it," among others.
But Steinmetz doesn't buy that, he wrote in the letter, "because consensual sex isn't something that men take from you; it's something you give. It doesn't lessen you to give someone else pleasure. It doesn't degrade you to have some of your own. And anyone who implies otherwise is a man who probably thinks very poorly of women underneath the surface."
His letter mixes sex-positive messages like this one with the teary inspirational language of a commencement address:
"Now, you're going to get bruised by life, and sometimes bruised consensually. But I won't tell you sex is bad, or that you're bad for wanting it, or that other people are bad from wanting it from you if you're willing to give it. I refuse to perpetuate, even through the plausible deniability of humor, the idea that the people my daughter is attracted to are my enemy."
He urges her to "find the things she f-ing loves, and vice versa."
Steinmetz, a science fiction writer, wrote on his Twitter account that he has two daughters, ages 21 and 27. They are lucky. If nothing else, they will get one thing that, in a society closer than ever to gender equality, young women still rarely do. Along with knowing that they can ask questions and talk in confidence about sex, their first awkward, clumsy sexual experiences will have been met with an accepting, reassuring — and yes, perhaps even congratulatory — pat on the back.