What if you wrote to the Baseball Hall of Fame offering to donate a full set of Mickey Mantle's toenail clippings? Why, they'd be glad to have 'em--even if you are "a Level 4 bed-wetter." Cooperstown is only one of many institutions terrorized in Letters from a Nut, a collection of crazed correspondence by Ted L. Nancy. The name is a pseudonym, perhaps for Jerry Seinfeld, who wrote the introduction. Seinfeld never comes clean, but the yocks sure sound like his material. And the letters have his prints all over them--who else would write the L.A. Lakers posing as a rabid fan who wears pants with a see-through back end, "for medical reasons"? Whoever wrote it, the book's a real lark. Where else can you meet "Pip, the Mighty Squeak," a man who gambles in a giant shrimp costume, or a corn that looks like Shelley Fabares? Only inside the fevered brain of Ted L. Nancy--whether he's Jerry Seinfeld or not.