One arm is a skill-shot that nets you a prize, the other arm knocks the target into the air... this skin seemed like an obvious conclusion!
I imagine custom lines like 'step right up', 'roll up roll up' and 'test your skill'. Also when ranged attacks hit him there should be a nice *ding* noise as a duck gets hit. Maybe depending on who kills him he leaves a varying size soft toy prize? Caitlyn custom line on ultimate 'I want the giant teddy'.