On Denshi Jisho looking up "おとこのこ" brings up two results:
男の子 and 男のコ
Edit: (child not boy)
I read the first one literally as "Male [possesive] child" or "Male's child" (or maybe の here is not a particle, just part of the word). The second one is strange. They have the same definition. Why do we have a Katakana コ here?