that red thing superman wearing is not for him it is for superwoman. Superman original color is also blue (for man) and that underwear he wears is red(for woman)by mistake in a hurry saving the world he just fly and take superwoman red bikini ;)
This is the reason why there is Superman I,II,III,IV and so on and there is only one movie for Superwoman becoz no more underwear for her...LOOOLssss