"My aim is to shatter all the stereotypes the system has perpetuated for 20 years," he says in urgent tones. Then his editor, Mashallah Shamsalvaeizin, orders him back to work. "Please, he can talk for ever," pleads Mr Shamsalvaeizin. "But we are on deadline, and he is hours behind."
Mr Nabavy, who writes for the daily Neshat - meaning "joy" in Farsi - has the courage to puncture holes in the Iranian identity, and get away with it in a country where laughing and applauding in public are frowned upon and sometimes banned. A liberal, he says, does not smell or wear a tie - behaviour epitomising a Western imperialist. Iranians, he writes, are all masochists, imprisoned by their self-concocted conspiracy theories.
The reason he has become a national celebrity tells the story of the new Iran. At last his readers feel free to indulge in comic relief, after years of ideological jargon in the official press which declares Iran's perceived enemies "hypocrites", Israel the "Zionist entity" and America the leader of "world arrogance". Now, more Americans are visiting Iran, and Tehran is on the point of exchanging ambassadors with its erstwhile great enemy, Britain.
An independent press is the fruit of President Mohammad Khatami's deliberate campaign to unleash the power of the pen to create a civil society within Iran's Islamic system. A former newspaperman and minister of culture, Mr Khatami can point to the first stirrings of a free press as one of his greatest achievements since his election in May 1997. Neshat is one of a dozen reformist publications testing the limits of state tolerance. Two years ago, only a handful of journals and newspapers were available; nearly all were mouthpieces for the conservative clerical establishment. Now a booming press, with writers like Mr Nabavy, is escalating the power struggle between conservatives and reformers.
The volatility the emerging press brings to Iranian politics can be felt inside the newspaper offices, where editors carefully weigh each scribbled word of their enthusiastic young journalists, looking for what one executive described as the "red lines" which should not be crossed if the newspapers want to stay in business. Many of today's reformist editors and journalists were former hardliners or revolutionary zealots, now out to drag their readers through the same political conversion they underwent. These figures are feeding a national appetite for self-expression and a re-examination of contemporary history.
"The favourite pastime of Iranians these days is laughing at the authorities," jokes a jittery Mr Nabavy. The problem, however, is that the conservatives are not laughing back. If the extremists of the past are today's reformers, suddenly the entire body politic could turn. Such a prospect has prompted hardliners to counter-attack at opportune moments.
Ten days ago, the conservative-dominated parliament brought an impeachment vote against Ayatollah Mohajerani, the Minister for Culture and Islamic Guidance, the man in charge of the press. They clearly hoped to stop the presses by forcing him from office. He survived only with the support of dozens of independent-minded MPs who believe public opinion is turning in the reformers' favour. The vote of confidence has given some newspaper editors courage, but others fear hardliners will retaliate.
There are already enough examples of unexpected ambushes. Hardliners last month closed Zan (Woman), a newspaper which promoted women's rights, after a cartoonist poked fun at the Islamic practice of blood money. And a magazine called Ardeneh was banned for running an article criticising hardline efforts to ban wolf-whistling, laughing and applauding during the Shia Muslim month of mourning.
A reformist theologian, Mohsen Kadivar, was recently jailed for 18 months for "defaming the Islamic system". Part of the evidence against him was a series of essays for Khordad newspaper, criticising some of the most sensitive religious and political principles underlying the 1979 Islamic revolution.
When Khordad's editor, Ali Hekmat, reviewed Mr Kadivar's articles he never imagined a court case would follow. Mr Hekmat is a reasoned man who values intellectual debate: "I believe the evolution of human thought requires discussion." But Mr Hekmat was already on a list of some 180 writers and intellectuals who hardliners said should be killed, and the Khordad offices were bombed last autumn.