Well! Plans for Monday's White House Egg-Roll are the grandest ever laid. Each visiting tad will trip in through a gigantic Easter basket, and gather One Bright Autographed Wooden Egg Per Child. Eggcited members of Congress have chicken-scratched their autographs on some eggs. A thousand entertainers--including, of course, Frank Sinatra, Johnny Carson, Clint Eastwood, Donna Summer and Bob Hope--have done eggsactly the same. So has every athlete you can shake a foot at. Ronnie and Nancy have signed several joint eggs, as have George and Barbara Bush. Over Monday's festive scramble will hover Bullwinkle. (Remember? The best-beloved balloon from Macy's Thanksgiving Day Parade.) Marvin Hamlisch will conduct the Marine Band. Willard Scott will cluck of the Weather, Ear hopes in a bunny suit. Gunther Gebel-Williams, the bonny blond lion-tamer, will leap in toting baby lions and tigers, and frolic photogenically with them. "Annie" will spring in. The Pirates of Penzance will prance. The Smithsonian will send its kite show. There will be an eggshibit of the eggs eggsecuted by Eggsemplary Contemporary Artistes, from Eggspressionists to Yolk Art. Ear means Folk Art, of course. You get the picture. It will stop now.