Megan Fox is not a man.
The rumour was sensationalize by a satire tabloid called 'Weekly World News' who published the article "MEGAN FOX IS A MAN!"(
http://weeklyworldnews.com/celebs/4783/megan-fox-is-a-man/) after Megan Fox herself made a random comment about she looking like a man at the red carpet of the Golden Globes Ceremony. The story was carried by other netizens and became viral.
Most people took the story seriously but what they didn't know is that WWN is actually a tabloid that creates fictional stories and is responsible for other satire articles like "MICHAEL JACKSON FAKED HIS OWN DEATH?" (
http://weeklyworldnews.com/headlines/9352/michael-jackson-faked-his-own-death) and "OBAMA NOTRE DAME SCANDAL" (
http://weeklyworldnews.com/politics/7192/update-notre-dame-scandal/).
There you go. Case closed!