GI’s in their foxholes, the way the ads used to tell it, passed their few sleeping hours dreaming about mother’s cooking or Rover, the faithful terrier they left behind. But to judge by the number of veterans now attending the Arthur Murray Dance Studios under the GI Bill of Rights, what they really dreamed about was learning to tread a graceful rumba. Murray, who calls himself “The World’s Most Famous Dancing Teacher,” has thousands of them pirouetting experimentally in his studios at government expense and he expects to produce at least 100,000 finished products within the next year. The idea started as a joke. Early this year, a former GI who was polishing up his samba in Murray’s New York studio remarked wryly that Uncle Sam should be footing the bill under the GI Bill of Rights. It had not previously occurred to Murray that a dancing school might be officially regarded as an educational institution. But, sighting a gold mine, he had a lawyer look up the terms of the GI Bill of Rights and concluded that a veteran studying to be a dancing teacher could qualify for government payment. A modest ad in the New York Times brought several hundred applicants and by April the first class of ex-servicemen was dipping, swaying and Lindy-hopping all at Uncle Sam’s expense.