line dog; line doggy; line doggie noun an infantry soldier US
In Vietnam, he goes by an assortment of names–the Grunt, Boonie Rat, Line Dog, Ground Pounder, Hill Humper, or Jarhead. — David Reed, UpFrontinVietnam, p. 3, 1967
“Hey, someone take my picture,” the line doggie yelled. — Larry Chambers, Recondo, p. 100, 1992