"I'll use this spoiled page to write down "dirty" jokes", she wrote-then listed four, along with an imagined lesson on sex education and some information on prostitutes.
Anne published two version's of her diary, these pages were found in the first copy, intended only for her self.
Frank van Vree, director fo the institute for war, Holocaust and genocide studies NIOD, said that he is "well aware of the paradoxical meaning" of the newly released texts. "They bring us even closer to the girl and the writer Anne Frank".
Another joke she had heard: "Do you know why the German Wehrmacht girls are in Holland?"
"All men, if they are normal, go with women, women like that accost them on the street and then they go together", wrote Anne.
The Anne Frank House Museum said at a presentation that it, and several Dutch historical institutes, were able to reproduce the lost pages after years of study by shining a light through them and photographing them in high resolution. "Papa has been there".
The jokes were written just two months after the then 13-year-old and her family went into hiding to avoid being captured by the Nazis.
The pages were covered by plastering brown paper over the text in the infamous red and white notebook.
Peter de Bruijn, a senior researcher at the Huygens Institute for the History of the Netherlands, which also partnered in the research, suggested to The New York Times that Anne may have edited the pages because she hoped to have her diary published one day.
Another discovery behind the masking paper was writings showing Anne had a good understanding about sex and sexual development.
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"Anne Frank writes about sexuality in a disarming way", said Ronald Leopold, executive director of the Anne Frank House.
Included on the pages were dirty jokes and writings about sex, libidos and periods.
He also announced that, while the full content of these pages has not yet been revealed to the public, the Anne Frank House does intend to publish them.
The Independent says she "attempts an answer, addressing an imaginary listener with a lofty tone, using phrases such as "rhythmical movements" to describe sex, and "internal medicament", to refer to contraception".
Only Anne's father, Otto Frank, survived the war.
In 1944, the Frank family was discovered, arrested and sent to separate concentration camps.
Mr Leopold said it shows how Miss Frank "creates a fictional situation that makes it easier for her to address the sensitive topics that she writes about".
Portraits of Anne (right), her sister Margot (center), and mother Edith (left), inside the Anne Frank House.
The house where the Franks hid has been turned into museum, making it one of Amsterdam's most visited attractions.