pound sand

Etymology
Probably originating as a mild insult, as the act of pounding sand is considered not only to be a menial task, but also one which causes no fruition, therefore suggesting those who perform it are somehow hopelessly mentally impaired.

Verb

 * 1)  To engage in a futile activity.
 * 2)  To go away; get lost; go to hell.
 * 1)  To go away; get lost; go to hell.
 * 1)  To go away; get lost; go to hell.

Synonyms

 * get blood from a stone, piss up a rope
 * get lost, go fly a kite, take a hike, fuck off