Inside NZ: The Naked Penis - Diddle, John Thomas, schlong ... giggle, giggle, giggle.

That's how this documentary starts, but it moves pretty quickly to information that everyone should have (parents, tape and keep), on anatomy, circumcision and self-examination for testicular cancer.

As in The Naked Breast, where a series of morphing breasts were used as a linking device, there's a morphing willy line-up - so be warned, there really are naked penises here.

Another linking device is the ebullient young Isaac, whose pronouncements range from "I reckon it's quite big, yeah" to "I'm just glad I've got a foreskin, eh. It's a primo little thing."

There's plenty of stuff here that could make a bloke feel secure. Flaccid size can have no bearing on erect size - "the locker room observation is entirely unscientific," according to anatomist Ken McGrath. And, for the record, "women do not care about size as much or even at all compared to men," says Bridget.

Dr Chris Henry explains in detail how to examine the testicles and Rob recounts his own discovery of testicular cancer - the most common cancer for men under 30.

Plastic surgeon Peter Walker demonstrates, using a folded hanky, how male genitalia is turned into female, and transgender Joanne jokes that she's now an amputee and should be allowed to compete in the Paralympics.

Of interest to mums is the circumcision information - the high rate of circumcision here and in Britain after the war is put down to "the sand myth" by anatomist McGrath, who finds it "very curious" that mothers were told their sons would have problems if they had to fight in another desert war.

Meantime, Dale describes his adult operation due to a tight foreskin. It's all here alright: vasectomy and vasectomy reversal, an eye-watering willy piercing, and even some talk of willy tattooing.

Just to show that men aren't one amorphous willy-owning blob, those interviewed here have a range of views on most things, from "I'm not having a vasectomy and that's it" to "I need to stimulate the erogenous zones by putting a bit of metal through it."

The last word must go to Isaac: "It's been a good thing to have a dick, I reckon. Everyone should have one."

* Inside NZ: The Naked Penis, 8.30 pm, TV3