The thing your aunt gave you which you don't know what it is is a semi-infinite storage device in the Hitchhiker's Guide to the Galaxy text adventure game. The only item that cannot be carried in or with the thing is the spare Improbablity drive.
If the thing is ever lost, it will return to you within a few turns.
Come to think of it, you vaguely remember an instruction manual with directions for that. You never read it and lost it months ago.