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 Anne Frank Foundation announced the discovery Tuesday, saying it helps to explain her adolescent interest in sexuality.
She wrote the recently discovered pages on September 28, 1942 at the age of 13, about three months after the Frank family went into hiding, and later covered them up with brown paper, the Associated Press reports. The Anne Frank House said it used new "image processing technology" to decipher the covered pages.The Franks were caught by the Nazis in 1944.
In her diary, she wrote about other jokes that were sexual in nature, discussed her changing body and menstruation, and explored her own budding sexual feelings toward members of the same and opposite sex. "They bring us even closer to the girl and the writer Anne Frank".
On October 3, 1942, she wrote: "Daddy is grumbling again and threatening to take away my diary. From now on, I'm going to hide it".
And about prostitution, she observed, "All men, if they are normal, go with women, women like that accost them on the street and then they go together".
On July 6, 1942, they retreated into the secret annexe of another home as the Nazis were rounding up Jewish families following their invasion of the Netherlands in 1940.
"I sometimes imagine that someone would come to me and ask me to inform him about sexual subjects, how would I do that?", she wrote.
The Anne Frank House, a museum located in Frank's former hiding place, did not quote directly from the text it had recovered. Her diary was published two years later and has been read worldwide and translated into at least 60 languages.
Some months after covering over the first entry "she emphasised the importance of good and thorough sex education, and she didn't understand why adults were so secretive about it", it added.
She died at 15 in the Bergen-Belsen camp, along with her sister. "At the end she explicitly names her father, Otto, who had been in Paris and saw houses with prostitutes", the Anne Frank Housewrites. In 1998, five additional pages were released-pages that dealt with what Anne saw as the strained and false relationship between her parents. During her time in hiding, she wrote two versions of the diary.