Justin Bieber Anne Frank ... She Couldn't Resist Me

4/14/2013 7:00 AM PDT

Justin Bieber: Anne Frank Couldn't Resist Me

Justin Bieber thinks he could have made Anne Frank one less lonely girl ... yes, what you are about to read is shocking.

Bieber visited the Anne Frank House in Amsterdam Saturday. According to the Facebook page for the museum (yes, the Anne Frank House has a Facebook page), Bieber was there with a few friends and bodyguards and went inside while a throng of fans waited outside.

The museum then explained ... "He stayed more than an hour in the museum. In our guestbook he wrote: 'Truly inspiring to be able to come here. Anne was a great girl. Hopefully she would have been a belieber.'"

Had she lived ... the April 13 diary entry would surely have included the word "douchebag."

A source connected to Bieber contacted TMZ and said the Biebs spent a full hour in the museum learning about Anne Frank. One of the things he learned was that she was really into the pop culture of the time. The source says that is why he wrote his "Belieber" comment.