Gynandromorphy is a condition caused by an unequal distribution of sex determining chromosomes in early mitotic division. this can lead to a scenario where some of the cells in an organism are male and some are female. if this condition occurs early enough in embryonic development it is possible for an organism to be divided bilaterally into male and female halves. this condition is most often observed in insects but has also been seen in birds and crustaceans.
Gynandromorphic cardinal. image source http://whyevolutionistrue.wordpress.com/2012/09/04/a-gynandromorph-cardinal-one-half-male-the-other-half-female/