The act of stuffing ones ass with as much sand as possible, squatting down and then letting the sand slowly pour out into another persons' gaping anus. If all the sand has been transferred, switch positions and repeat. Bonus points if you can get some consistency going e.g. switching every 10 minutes.
Alex: Bro, we really gotta start practising our hourglassing
, our times are all over the place
Tim: I'm not your bro
, fucker. Now hurry up with the sand.