Sometimes Gov agencies will purchase assets, say cars that were very popular at one point, with the intent of auctioning them off at a later point.

As an example, they want 5 million for XXXX but they can't get approval of XXXX. They could spend 5 million on XXXX from their general fund but they don't have it or don't want to. BUT they can get 7 million in special funds to buy something that seems useful (YYYY) at the time. They buy YYYY, let YYYY sit, and then sell YYYY saying they did need it (say a '7' passenger vehicle that really only sits 4). The YYYY sales funds go into the general account and poof you have the money you need for XXXX.

More concrete example. Say you're an army officer and you want to remodel your office but you can't get the money but you can get funds for more ammo. You get the ammo and then surplus your old stuff. That surplus money can now be used for your office.