NOT long ago I was struggling against the motley stream of lunch-goers that had spilled out onto Madison Avenue from hundreds of pastel-walled agencies that infest that area. My mind was, as usual, operating at half-mast, idling along, picking its own daisies and bothering no one. I was heading for my favorite French restaurant, "Les Miserables du Frite," where I was meeting a fellow Expense Account Cheat for another 31/2 hour lunch on the Internal Revenue Department. Now, I had passed this corner countless times before, with no noticeable traumatic effects. Today was different...