Anonymous Garbage Collected/Temporary Collection

It would be useful to be able to create temporary anonymous collections, in order to fake big transactions.

Right now (in java) I am using the hack of running a .find() on a new collection that I make, and then a .toArray() on the cursor that is returned, and then inserting the resulting list to my main collection. Then I drop my collection. But even if I forgot to drop the collection, it would be nice for it to disappear. Also, it is annoying to have to generate a random string to support multithreading this.