There are two kinds of standing ovation. One is the obligatory kind audiences give, say, a national touring production of Fiddler on the Roof. It's our way of acknowledging the institutional character of the experience, the fact that were seeing a show that thousands have seen before us and ratified as "classic." We're applauding the sweet familiarity of the thing. The other kind is the more raggedy kind Spalding Gray got last night, Tuesday night, after performing his evening-length monologue, Monster in a Box. That's the one that comes when we know we've seen something nobody's ever seen before--because it's too special, too unique, too particular to a moment and place. A WASP Woody Allen with intimations of Emersonian transcendence, an egocentric east-coast neurotic with moments of perfect lucidity, Gray tells a story that no one else can tell. It belongs exclusively to him, both in content and in sensibility. What's a cliche about others is plain fact about Gray: you simply must see him. See him twice, in fact: Gray's offering not just one but two monologues during the course of this very brief run--the aforementioned Monster in a Box, which is about "a man who can't write a book about a man who can't take a vacation," and Terrors of Pleasure, which I'm going back to see tonight. Goodman Theatre, through September 9; Thursday, 7:30 PM; Friday and Saturday, 8 PM; Sunday, 2:30 PM. The schedule follows. Monster in a Box--Thursday and Saturday. Terrors of Pleasure--Friday and Sunday. $18-$20.