After years spent keeping political texts off the printing presses, authorities are setting their sights on the growing market of publishing for young people, with several books prohibited in recent months.
Nguyen Thanh Phong, whose collection of comic rhyming slang was recently banned, said his illustration of two gormless-looking soldiers kicking a grenade to each other may have caused the censors' ire.
The caption reads "Being a soldier you must always get noticed", an attempt to poke fun at the inflated, heroic image of the country's military.
"I just thought it was funny," said Phong.
The 26-year-old artist said censorship only increased people's desire to read the book, entitled "The murderer with a pus-filled head", which aims to reflect the street patois of Vietnam's youth.
Phong said his book sold 5,000 copies in two weeks but was then discontinued, stoking under-the-counter demand that pushed prices to as much as 100,000 dong ($5) -- more than double its official cost.
Censorship has proved a headache for Vietnamese publishers eager to capitalise on a potentially rich seam of revenue from the nation's 28 million under-18s, but it has also given texts an enticing air of notoriety.
"It's an unintended public relations chain effect -- in Vietnam, any banned books become best-selling, because people are curious," Phong told AFP.
The controversy "sparked the interest of a lot of people who would never have even bothered to read it in a bookstore," said Vietnam expert Edmund Malesky, Associate Professor at the University of California, San Diego.
He added the book "captures all the cool sayings of what they call the 9X generation, those born in the 90s", a generation surprising older Vietnamese with its "free-spiritedness".
Conservatives in Vietnam have found themselves scandalised by the tide of youth culture -- from the antics of popular singers to brazen fashion statements on the streets.
The publishing industry is seeing a boom in titles for teenagers, varying from non-fiction to translations of the internationally best-selling "Twilight" vampire series.
Vietnam scholar Carl Thayer said more books are being produced aimed at young people, but that "pop culture is definitely at odds with official ideas of Vietnamese culture".
"Since Vietnam is an authoritarian regime, its officials have no way of accurately capturing true public opinion... Deep in their hearts they are fearful of political humour and more overt political publications because it challenges their power and legitimacy," he told AFP.
Reporters Without Borders, which ranked Vietnam 165th in the world for press freedom out of 178 countries in 2010, has said the one-party state retains a tight grip on all media.
Vietnamese officials were unable to provide AFP with figures on the number of books banned each year and did not confirm the specific reason for the decision to take Phong's book off the shelves.
Dang Thi Bich Ngan, deputy director of the culture ministry's Fine Arts Publishing House, said sales of "The murderer" were stopped because of changes made to the approved draft.
Another controversial book, a collection of short stories by journalist Nguyen Vinh Nguyen, was banned and its publisher fined for "disseminating depraved and pornographic ideas, not in accordance with Vietnam's traditions and customs".
"Readers really want the sort of products of a free publishing environment, rather than what they are given now, which are books that have undergone 'treatment' and been sanitised," Nguyen told AFP.
Thayer said Vietnam's black market "thrives because it meets a need".
"It provides hard copy of facts and ideas that freely circulate in private conversations," he said.
It did not take long for AFP to track down an illicit copy of "The murderer" on the streets of Hanoi.
One bookseller said she did not keep it on her shop's shelves and offered to fetch one from the storeroom.
But her sales pitch came with the warning that it had corrupted the Vietnamese language: "Do not show it to your children!", she said.
Many people simply went online to read Phong's book on the numerous Internet sites hosting copies.
"Those who object to the book said if these sentences are circulated on the internet, it's ok, but not in books. I think because they think books are very noble, like a holy land of knowledge," Phong said.
Censors have indicated a willingness to negotiate a revised version.
Phong said he expects some illustrations will be removed and replaced with different popular slang and is confident a new book would not be seen as diluted.
His optimism is perhaps echoed in another quintessentially Vietnamese street saying from his book.
An image of a whole dead dog on a dinner plate accompanies the phrase: "Don't worry, things will be alright, because dog meat is always served with shrimp sauce".
