At the first bars of "My Heart Will Go On" from the hit film "Titanic," the men pushed their grilled sandwiches and French fries to one side and began whistling in unison.

Such displays are not unusual for these members of the Indian Whistlers' Association. In fact, they see it as an essential part of their mission to raise the profile of a much-derided activity.

"The most important thing is that whistling should be recognised as a performing art," said Manoj Karam, a 44-year-old IT professional who acts as the group's co-ordinator in western India.

"Right now it's not taken too seriously. Some people think we're just joking or just doing it for fun. But we're doing it to portray it as an art form all over India."

The IWA bills itself on its website as "the first, truly Indian whistling community".

Set up by Rigveda "The Maverick Whistler" Deshpandey in 2004, it now has nearly 400 members across the country, of all ages and from every walk of life.

Potential new recruits are put through their paces in a telephone audition to show they can whistle both in tune and with a "polished" sound. They are then quizzed about whether they are prepared to spread the word of whistling.

If a person makes the grade, they are given suggested songs to practise and breathing control exercises.

At this point many realise that you don't just put your lips together and blow.

"It's not as easy as it sounds, whistling the tune, breathing at the right point," said Sharad Karnad, 44, a civil engineer in the energy sector.

"Pucker whistling" through pursed lips -- the most common form and the easiest way to carry a tune -- requires as much work to perfect as singing in a choir, he said.

-- From Bollywood to Berlin --

No one in the group can say exactly when they took up whistling.

"People don't know for the simple reason that you didn't recognise it as an art form," said 30-year-old Aditya Kothari, a founder member of IWA who works in retail marketing. "Practically everybody just started from childhood."

In the universal language of whistling, language and culture are no barriers. Kothari's mobile phone ring-tone is of him whistling the jingle from a television coffee advertisement.

"As long as it has a tune, you listen to it, feel it and try to replicate it," said 31-year-old lawyer Chetan Bhide, another founder member.

All five men are big fans of Bollywood, particularly songs by Kishore Kumar and Mohammed Rafi, legendary "playback" singers whose songs are lip-synched by actors in Hindi-language movies.

Around the country, Hindustani classical and southern Carnatic compositions are popular, as is Western pop.

Uday Shirur, 44, cites Stevie Wonder's "I Just Called To Say I Love You" as a long-time favourite.

Others say the likes of "Careless Whisper" by Wham!, Phil Collins' "Another Day In Paradise" and "Take My Breath Away," soft rockers Berlin's theme from the Tom Cruise blockbuster "Top Gun," are top tunes to whistle.

-- Women, snakes and world records --

As well as popularising their brand of music-making through live concerts, workshops and media appearances, the IWA also aims to shatter myths about whistling -- and boost its female membership.

At present, there are only about 15 women in the association, something Karam blames on the taboo of women whistling in India and the negative connotations of wolf-whistling.

"People have that idea in mind," he said. "The first impression is he's whistling, so he's doing something bad, he's eve-teasing (sexually harassing women).

"That was the case for men, so if a woman whistles it's extraordinary, something is wrong. That's why we're promoting exclusively women's shows."

Kothari offers another reason for whistling's bad press: "If you whistle at night it's assumed you're calling for snakes. It's a bad omen."

The IWA this year entered the Limca Book of Records -- India's equivalent of the Guinness World Records -- for the highest number of whistlers whistling a tune in unison.

Forty-eight whistlers puckered up for a rendition of India's unofficial national anthem, the patriotic "Sare Jahan Se Accha," one of several tunes to be found on their dedicated YouTube site.

They are now gunning for the Guinness title with 100 whistlers and want to bring the International Whistlers Convention to India.

Shirur says whistling is as good as yogic breathing exercises and a perfect stress reliever. Kothari calls whistling "lung fu" as it builds lung capacity.

"If I'm not talking, I'm whistling," he said.