If you are channel-surfing late some night through your higher cable channels, you may come across a woman who looks rather like an elderly nun, thrusting a model of a male sex organ into her fist. Her name is Sue Johanson and she is very strange.

Johanson hosts a live call-in show on the Oxygen network in which she answers sex questions, rates sex toys and offers historical sex trivia. She is married with grandchildren, owns a cottage north of Toronto, sews her own clothes and curtains, and sometimes fashions homemade sex toys.

On "Talk Sex With Sue Johanson," the 70-ish host takes calls from all manner of people -- pregnant women, insecure men, obese women with obese husbands. She offers medical advice, allays concerns and exhorts her viewers to go out and try new techniques with the relentless enthusiasm of a phys-ed teacher.

"It's going to feel strange at first, but you won't die!" she advises the ill-named Chastity, who has queried about an unorthodox sexual position.

Johanson has been on the air in Canada since 1996, and tomorrow she starts the third season of her U.S. show. She was in New York this week to appear on "Late Show With David Letterman," during which she teased the host about his sex life and discussed his baby son's genitalia at some length. She'd sewn a cute black skirt especially for the occasion. Unfortunately for viewers, Johanson was not as playful as she had been in a 2003 appearance on "Late Night With Conan O'Brien," during which she strapped a sex toy to her chin and thrust a vibrator into Tom Selleck's mustache.

Johanson had lunch beforehand at a place called Redeye Grill in midtown. She ate gumbo, discussed her recipe for Swedish meatballs, and complained about something she'd eaten the day before that had given her -- well, we won't repeat exactly what she said, out of deference to your Bran Flakes. As a general matter, Johanson delights in discussing bodily functions of all sorts. She made three fart references during lunch. She particularly enjoys those calls she gets on her show regarding farts during sex.

"Sex is funny," she says. "Think of the positions you get into."

A nurse who lives most of the year in Toronto proper, and broadcasts from there as well, Johanson has been lecturing about sex for nearly 35 years. She has written books and lectured extensively at high schools and colleges across Canada. For almost 30 years, she ran a free birth-control clinic that she'd founded at a Toronto high school. She is adamant about the use of condoms (her pronunciation renders the word "con-domes") and answers a lot of worst-case-scenario questions from her "Talk Sex" viewers. ("You can get gonorrhea in the back of your throat," she tells one guy.) Before and after commercials, Johanson's show -- which airs at 11 p.m. Sunday and in reruns the rest of the week -- gives phone numbers for HIV help hotlines and carries safe-sex reminders such as "Cover Mr. Twitchy, or you'll wind up itchy!"

But most of the time, Johanson -- a gray-haired woman who wears baggy clothes and round glasses -- adopts the gung-ho attitude of a Girl Scout leader high on Do-Si-Dos.

She jams sex toys into her hand to show how they should be used, or drops them and laughs as they hum and bounce across her desk. She rubs strawberry warming massage oil on her hand. She uses articulated wooden dolls to demonstrate sexual positions. She pretends to have an orgasm, closing her eyes and gripping the desk. She launches into long, happy soliloquies, such as this one, in response to a woman who calls in about her fiance's foot fetish:

"Your partner is turned on by feet! And he likes to touch them and rub them and massage them. . . . He likes to smell them, to kiss them, to lick them and suck them!"

The caller is silent, perhaps more alarmed now than ever.

"You still with me?"

On another occasion, Johanson promises that in the next episode, she'll be showing off homemade sex toys:

"You will never look at an electric toothbrush the same way again!"

Most of all, Johanson urges her viewers to pursue their heart's desires, and to "Have fun!" Lunch with her proves that her enthusiasm extends beyond sex. She loves baking pies; she loves her new lipstick; she loves the $29 blue leather shoes she's wearing. She says, "Oooh, I loooooove to sew." When the food arrives, she says, "I'm gonna try that little bit there," and stabs something on a reporter's plate.

She eats her gumbo, requests another roll and lists the questions she gets on her show.

"Viagra. We went through that. And G spot. And orgasm."

She tears at her roll, then says, "What's that?" pointing at her publicist's plate with her fork. The publicist forks the piece of food onto Johanson's plate.

Johanson says she's been careful about her image. She won't discuss her sex life and never gives her age in interviews, an odd bit of reserve for a woman who will flick her tongue wildly at a camera. In truth, she is better on television, which caters to her self-described hamminess, than she is in print interviews, where she often gives one-word answers and avoids eye contact. She says she has made a concerted effort not to become like Dr. Ruth Westheimer, the sex therapist who had her own board game and starred in a French movie.

Johanson says she wants her image to be "more of an educator than an entertainer. And I am very, very careful about what I do, what shows I will appear on. And I've also got to be careful about overexposure."

In the United States, she's not in danger of that just yet. Oxygen is a struggling network, and "Talk Sex," one of its most popular shows, averaged fewer than 300,000 viewers per episode last season.

Johanson says that in Canada strangers will often corner her on the street with personal sex questions, but Americans -- even those who recognize her -- are more likely to keep their curiosity to themselves. She is convinced Americans are too embarrassed about sex; Canadians, she says, are much more comfortable.

"Now think of your co-workers," she says. "Are they open and right-up-front about sex?"

Uh.

Johanson starts to explain what it's like in her workplace.

"But we're different," Johanson's producer, Julie Smith, interrupts. "We sometimes don't realize that not everyone -- "

"Walks around with a dildo in their purse!" Johanson finishes triumphantly.

What magic there must be on the set of "Talk Sex." Johanson brings in sourdough biscuits every week, which she makes from a culture she's been keeping for 38 years. Sometimes, her staff comes up to her cottage and plays croquet. One time recently, she says, she provided sex toys, which were placed -- buzzing and revolving -- on the croquet course.

"You had to hit the dildo with the ball!" Johanson says.

The waiter comes to take Johanson's gumbo away.

"Oh, Sue!" says her publicist. The sleeve of Johanson's white sweater has dropped into her gumbo.

"Oh," Johanson says good-naturedly, making a dismissive flapping motion with her wrist. She takes a napkin and starts to rub at the stain.

"I told you: You can dress her up, but you can't take her anywhere," she says.

Sue Johanson hosts an utterly unsqueamish live sex advice show on the Oxygen network. Aside from her wisdom, Johanson offers tips on sex toys and even a little trivia.The good-humored host of "Talk Sex," Johanson has lectured about sex for nearly 35 years. "Sex is funny," she says. "Think of the positions you get into."