The phrase "pound sand" is a colloquial expression that means to go away or leave because you are not wanted or your action is not valuable. Full definition
Sometimes when we hear this advice, all we want to do is tell them to go pound sand. (halliecrawford.com)
Then lay a 10 - pound sand bag on each inner groin, parallel to the crease between the thigh and pelvis. (yogajournal.com)
Just be cognizant that there are many in this industry who would of told you to pound sand so make sure to brush up on your due diligence. (biggerpockets.com)