Like 69'ing but standing up, the partner holds their partner whilst performing fellatio. The carrying partner vigourasly shakes much like the emptying of a sandbag.
Last night we tried sandbagging, he emptied me everywhere and then I emptied him.
In gaming, the act of slowly leveling while otherwise increasing stats and currency in order to be stronger than other players at your same level; who have not sandbagged. Particularly useful in pvp focused games that pair players based on level.
you pick up a girl from a bar and make sure not to give her any personal info she can use to track you down. take her to the beach to screw. instead of putting on the condom as she requests, pretend to put it on but actually fill it with sand as you hit it raw. then after you nut in her, tell her what you just did and throw the condom of sand in her face, blinding her for a few minutes while you make your escape
When someone remembers all of your mistakes, almostlike picking up grains of sand and putting them in the bag. Then when they want to put people against you, they remind you of all of their mistakes, as if they were hitting you with the bag of sand.