MAYBE it's the expo sure, the vulnerabil ity or simply a white-hot resentment of men. But few things from Hollywood's greatest creative minds elicit the crowd-pleasing merriment of watching a grown man take a monster shot to the groin. Around since antiquity, assault on a man's nether region is enjoying a sort of renaissance — if such a highbrow word can be used in such a lowbrow context — becoming a virtual staple of the summer comedy, as evidenced in such current films as "Dodgeball," "Napoleon Dynamite," "White Chicks" and "Anchorman." There's a good reason for the lack of protest...