HEY! GIRLS JUST WANT TO HAVE FUN OFFSCREEN TOO

Some unusual chanting went on the other morning on trendy Melrose Avenue.

“Chicks rule! Chicks rule! Chicks rule! Chicks rule!”

After a few more choruses (delivered in Bronx truck driver -ese and punctuated with close-fisted, rigid arm thrusts), actresses Helen Hunt and Sarah Jessica Parker collapsed in a fit of giggles. The two stars of “Girls Just Want to Have Fun” seemed to be effortlessly living up to their movie’s title as they window-shopped and swapped stories about a recent trip to promote the movie.

“There was the guy at the San Francisco ABC affiliate whom they call ‘The Five O’Clock Shadow,’ who always wears a black hood when he reviews movies,” Hunt added. “He interviewed us real seriously out on the street, with the hood and everything!”

More laughs.

The actresses’ friendship, seen so clearly on screen, exists off screen as well. With some definite differences.

(In the film, Parker plays timid Janey Glenn, who--with help from unconventional best friend Hunt--enters the dance contest of her dreams.)

Hunt, rather than being a platinum-haired Peck’s bad girl, actually is ash-blond and poised beyond her 21 years.

(“Yeah, ever since I was 12, I haven’t gotten jobs playing teen-agers because I was ‘too knowing.’ ”)

On the other hand, Parker, 20, seemed the embodiment of mischievousness.

Parker’s hair is a natural tumble of curls, not like her character’s super-straight Wasp locks.

“Hair Hell!” both wailed about the only experience on “Girls” that wasn’t fun at all.

“Next time . . . a wig!” Hunt firmly stated, explaining that she had agreed to bleach her hair for the part. “I looked in the mirror after it was done and suddenly my identity and my own sense of beauty were totally thrown for a loop.”

Parker nodded assent. “Of course, then there’s me, Miss Hasidic Head. My hair was dyed (light brown) and straightened.” A sigh. “My hair was dyed years ago for another role and, you know, they can never dye it back right--hair hell for sure.”

However, hair was hardly all these two had to discuss. Both are show-biz veterans, though they arrived at their present roles in very different ways.

“My school days usually began at 6 a.m.,” Parker said of her Cincinnati childhood. “There were eight children (in the family). Two would practice on the piano, then switch with two others, while others would be playing viola and violin or working out on a staircase banister that doubled as a ballet bar. I was exhausted by the time I left for school.”

While neither parent was involved in show business, Parker said, “They put the utmost importance on fine arts.”

Parker hit Broadway at 11, when she and her brother were cast opposite Claire Bloom in “The Innocents.” (“My father saw the casting call in a local newspaper and took us to New York.”) That role led to others, including “By Strauss,” “The Nutcracker” and “The Firebird,” and the title role in “Annie” during the course of its long run.”

At 17, she received critical attention as one of the co-stars on the short-lived CBS series “Square Pegs” and also appeared in the TV movies “My Body, My Child” and “Broadway Plays Washington.”

Her film credits include “Footloose,” “First Born” and “Rich Kids.”

After spending most of her acting career in New York, Parker moved to Los Angeles last January with boyfriend Robert Downey, who appears in the coming “Weird Science.”

“We were both big New York advocates,” Parker explained, “but we were here so much of the time, and when we lost our New York apartment, we made the big decision.”

It was a difficult decision, she acknowledged. “I’m a real purist about the theater and that whole thing, and believed that no place was better. Now that I’m here, I love the life style,” she said. “My parents still think I’m coming home.”

Parker agreed to do “Girls” largely because she knew the screenwriter, Janis Hirsch, who was one of the writers on “Square Pegs.”

As a result, aspects of Janey Glenn closely resemble the way Parker behaved at 17, when she was doing the series. “Everything those days was either ‘the greatest’ or ‘the worst.’ I was always afraid.

“Besides that, Janis wasn’t into depicting people my age being stupid. I was impressed with her fondness for two best friends who aren’t competitive.”

Parker, cast in the movie first, said it wasn’t until she heard that Hunt was reading for the part that she got excited.

“I knew a lot of Helen’s work,” she explained. “She always seemed to be on the money; she was never a victim of overacting. I was thrilled when I heard she would be coming in for a reading--up until then I’d been kinda vague about the whole thing.”

“They were looking for Goldie (Hawn) types when I was called in,” Hunt recalled. “But the director (Alan Metter) pulled me aside and said, ‘Sarah would kill to work with you.’ ”

Hunt smiled. “It was really cool. Because I knew she wanted me to do the role, I felt I had the support to overcome my Sarah Lawrence looks.”

The daughter of theatrical director Gordon Hunt (who is also her acting coach), Hunt has been working since she was 9. She landed roles in a variety of TV films, including “Pioneer Woman,” “Quarterback Princess,” “The Miracle of Kathy Miller,” “Bill: On His Own” and “Choices of the Heart.”

Roles in several TV series, including “Swiss Family Robinson” and “It Takes Two,” plus a recurring role as Dr. Jack Morrison’s (David Morse) girlfriend on “St. Elsewhere,” made it possible for Hunt to buy a house in Studio City, which she shares with a girlfriend.

Once she was cast in “Girls” and had gotten past the shock of being a blond, Hunt said she was allowed to “get real creative with who Lynne was.”

To create the bizarre fashions her character bops around in, Hunt said she first “went out and bought all these European magazines--then I did everything that wasn’t in them.”

The actress said she thought much of her success in the film came behind the scenes. “I felt a responsibility to bring a sense of fun into the picture,” she explained. “And I knew that to do that, I had to have it for myself and then spread it around. So I brought Tofuti (the healthy ice cream) to the set and got a lot of tapes from Tower Records.

“It helped. When you’re making a comedy and it’s 2 in the morning and you’re tired and nothing’s going right, there’s no way you can cut ahead and think, ‘Boy, this is going to be exciting when it comes out.’ ”

What seems to have been the most exciting aspect for Hunt and Parker is the friendship they’ve established since “Girls.”

“Helen’s a staple in my life now,” Parker said. “Like rice. She’s consistently a cool person, a good soul . . . and so much fun!”