Go pound sand
An expression of disdain, along the same lines as 'get lost', 'go and play in the traffic', etc.
This is sometimes used with the intention of meaning 'go and beat/whack sand' - with the back of a shovel or similar. That's not the original meaning though, as is made clear from the longer and less-often used version of the phrase - 'go pound sand up your ass'.
The phrase originated in the US and although common there, especially the midwest states, it isn't frequently heard in other countries.
The version 'go pound salt up your ass' is also sometimes used, presumably to heighten the image of discomfort.
It may well date to the early 20th century. That version was certainly well enough known in the US in 1969 for Max Yasgur to have used it when arguing with local dignitaries over his bringing the Woodstock Music and Arts Festival to his farm in Bethal, New York, saying:
"Well, you can all go pound salt up your ass, because come Aug. 15, we're going to have a festival!"
There's also a less vulgar version, 'go pound sand in your ears'.
Here's an entry from the Southeast Economist, Chicago, 1948:
"From her store of memories Mrs. Mary R. Stuart of Harvard Ave, perpetrator of this column of sayings of wisecracks popular in the 'Oh yeah?' era, recalls that 'go pound sand in your ears' meant to soft-pedal the noise."