"A potato, being so knobbly in shape, requires an expert marksman to throw it" - PGW (I think it isn't completely word perfect, but at least, the first part is)
It just struck me this evening that my head seems to be like a potato, and requires an expert to make it look even somewhat presentable. It reminds me of an argument of the Outlaws - I think it's Ginger accusing William, or it could be the other way round (my memory isn't all that good), saying, "Your head is the wrong shape". Mine is, too!!!