Pound Sand Meaning

Example : 2010, Eric Blehm, The Only Thing Worth Dying For: How Eleven Green Berets Forged a New Afghanistan, HarperCollins (2010), ISBN 9780061661228, page 44:  […] Without men on the ground, we'll be pounding sand."2003, Christopher Koch, "Showdown at the 6.0 Corral", CIO, 15 March 2003:  "The price to us was going to be $3 million, and we had four months to pay before the Licensing 6.0 deadline. We told Microsoft to go pound sand."