If you know that “to
fuck” a person is to have sex with him/her, you automatically understand that a fuckable person is one that you would like to
fuck. Accordingly is an unfuckable person a person that you don't want to fuck at all. A refuckable person is a person you would like to
fuck again, while an unrefuckable person is one that you don't want to
fuck again. You know the meaning of all these words by virtue of your knowledge of the individual morphemes fuck, re-, -able and un- and the rules for their combination.