Fujoshi = Rotten Girl Fudanshi = Rotten Guy Basically Fujoshi is a rotten girl interested in Yaoi while Fudanshi is a rotten guy thats either gay or just likes Yaoi.
Because fudanshi just reverse the gender term for female(which is girls that likes Yaoi) and makes that term for guys that likes Yaoi(most of which some are gay).
So fudanshi refers to guy that likes yaoi. I didn't know that. I always thought it means that the guy likes yuri. Learning new things everyday.