DANCING IN THE NUDE, we suppose, can be like dancing in the dark or dancing in the rain -- a form of artistic expression entitled to the protection of the First Amendment. But somehow we doubt that the kind of nude dancing the Supreme Court addressed last week was of that character.

The justices were confronted with the effort of Mt. Ephraim, N.J., to keep nude dancers from performing within its boundaries. The dancers were the kind who perform behind glass before customers who stand in booths and put quarters in slots in order to get a glimpse of what is going on. Even without seeing them perform, we have little doubt about the message they were trying to express, and we're not at all sure it is entitled to the Constitution's protection.

That doesn't mean, however, that the court was wrong in telling Mt. Ephraim it couldn't do what it wanted to do to the adult bookstore providing this show. That community had tried to drive the nude dancers out of town by enforcing a zoning ordinance that purported to bar commercial estalbishments from offering entertainment for their customrs.

Broadly read, as the city fathers and the building inspector insisted it should be, that ordinance barred all entertainment. The borough's motion picture theater survived as a prior non-conforming use. Read more narrowly, as the lawyers kept telling the judges it should be, the ordinance barred only "live" entertainment. The music supplied by real people at the local clubs would survive as prior uses under this theory, but future performances of high school plays at which admission was charged might not.

Add to that confusion one other fact: Mt. Ephraim's city fathers didn't object to the bookstore's activities until it switched from showing "adult" movies in its booths to showing the real thing behind glass. You can't tell from the judicial record, as Justice Stevens noted, whether that switch "introduced cacophony into a tranquil setting or merely a new refrain in a local replica of Place Pigalle."

The difference is important. The court didn't rule that obscene nude dancing is protected by the Constitution. Nor did it rule that nude dancing is always protected wherever it occurs. The odds are that nude dancers, even if they have a simple, welcome-to-springtime type of message to communicate, can still be kept out of purely residential communities that bar all commerical establishments. And nude dancers with nothing but obscenity to communicate are still in trouble, if anybody can ever figure out how to define obscenity. Meanwhile, the show in Mt. Ephraim can go on at least until the city fathers write an ordinance that more specifically prohibits whatever it is they want to prohibit. And it might even be able to go on after that if the dancers would take up performing not only in the nude but also in the rain and, preferably, in the dark.