No one knows for sure if Apple really is announcing a bigger iPhone, but that hasnt stopped Samsung from taking yet another jab at its rival. The companys derisive new commercial shows a man excitedly commenting on rumors about the upcoming iPhone 6s screen size. His enthusiasm is crushed when his friend, who is glued to a Galaxy S5, asks, This hasnt happened yet? The 30-second video then continues with the narrator slyly alluding to the fact that bigger smartphones are available right now — if iPhone proponents are willing to defect, that is. …