pounding sand

Verb

pound sand (third-person singular simple present pounds sand, present participle pounding sand, simple past and past participle pounded sand)

1. (idiomatic, informal) To engage in a simple, useless activity that anyone would reasonably know how to perform.
   • "Bishop McKillup lives there. He's got only three wives, and they three all put together don’t know enough to pound sand with a mallet, with a receipt on the handle."
     For which striking symbol of imbecility I should have given Jake a good deal of credit, if I had not heard him using it several...1871 January, Everett Chamberlain, “My Christmas at Salt Lake”, in The Lakeside Monthly
2. (idiomatic, informal) To engage in a futile activity.
   • […] Without men on the ground, we'll be pounding sand."2010, Eric Blehm, The Only Thing Worth Dying For: How Eleven Green Berets Forged a New Afghanistan, HarperCollins, published 2010, →ISBN, page 44

   Synonyms:

   get blood out of a stone, piss up a rope, pound dirt, pound salt, pound sand into a rathole

3. (derogatory, idiomatic, slang, dismissal) To go away; get lost; go to hell; to waste one's own time (with some other meaningless task) rather than waste the speaker's time with something equally irritating or pointless.
   • All you do is complain. Why don't you go pound sand up your ass and stop bothering the line staff.

   Synonyms:

   get lost, go fly a kite, take a hike, kick rocks, fuck off