Anne Frank's diary contained musings about sexual education as well risqué jokes, which the teenager later tried to cover up with brown paper that she pasted over two pages.
"I'll use this spoiled page to write down 'dirty' jokes," she wrote on Sept. 28, 1942, after hiding in the secret annex for several weeks, according to the Anne Frank House.
In addition to the four "dirty" jokes, the two covered pages also contained five crossed-out phrases, 33 lines about sex education and mention of prostitution.
However, only now have researchers been able to read the text from Frank's world-famous wartime diary through the use of digital photo editing techniques.
The Anne Frank Foundation announced the discovery Tuesday, saying it helps to explain her adolescent interest in sexuality.
Frank van Vree, director of the Netherlands Institute for War, Holocaust and Genocide Studies, said that anyone reading the passages would be unable to "suppress a smile," adding that the "dirty" jokes, which are "classics among growing children," made it clear than Frank was "an ordinary girl," according to Huygens ING.
Writing about sexual education, Frank said: "I sometimes imagine that someone might come to me and ask me to inform him about sexual matters," The New York Times reported.
"How would I go about it?" she pondered.
Writing about prostitution, Frank noted that all "normal" men "go with women, women like that accost them on the street and then they go together," according to The Washington Post.
"In Paris they have big houses for that. Papa has been there."
Frank's diary has become a significant beacon in the fight against anti-Semitism.
So much so that last year the Italian soccer federation announced it would be reading excerpts aloud at all soccer matches in Italy for a week in the wake of shocking displays of anti-Semitism by fans of the Rome club Lazio.
"Anne Frank doesn't represent a people or an ethnic group. We are all Anne Frank when faced with the unthinkable," Italian Foreign Minister Angelino Alfano said at the time.