With upward of 60,000 "Fat Lady" T-shirts sold since her buxomness sang for the Bullets, get ready for another proliferating slogan next to your skin:

THE RHYTHM IS WITH 'EM.

'Em being Your Redskins, with Fred Fillah, president of the Shirt Xplosion, Hyattsville, seizing onto something much bigger than the NBA champions if he knows his business. Fillah projects an issue of 150,000 of the Redskin T-shirts, with 300 stores lined up to peddle them: S6 a pop.

That's coming a long way since Fillah did the original Over The Hill Gang shirts of Super '72 - sales approached 20,000 on that number.

The T-shirt man told The Post's Len Shapiro he got the idea for the slogan from stories in your morning paper in which Joe Walton and Joe Theisman, and then John Riggins, cited rhythm as the key to success.

And, fittingly, since Riggins said, "A big part of gaining yards is getting your rhythm and you have to carry the ball a lot to get into it," the shirt will have a background portrayal of a playing field with a ball carrier who will look suspiciously like No. 44.

Oh, basketball still gets a call, says the T-shirt man. Another Bullet operatic shirt is in the works. Something about "ENCORE!"