To boil broccoli is to watch pornography, because watching pornography is like boiling broccoli because you have to watch the broccoli when cooking it so the broccoli doesnt get too soft- like the 'other' thing that might get soft when watching pornography.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi