A 'cuug' is a derogatory term for person who thinks they are clever by combining two words in to one for the sake of doing it.
It is self referential, in that it itself is a combination of two words, but the original two words have been forgotten by some mug cunt.
That cuug James created another word, he is such a cuntwat.
Simply a mixture of a 'cunt' and a 'mug'.
That ginger cuug-boy