lol well like I said it'd be a bad idea... but ...
a vendorless user based contest where people are allowed to enter one time only, for a random number drawing, where the winning prize is that everyone who entered and lost has to send an item of their choice that they don't need/want from their collection to the winner. Could be anything from carts(unused obviously), a bottle of liquid, spare atty, spare batt, pretty much anything.
But obviously that would be an "on your word" type of contest and would then end up causing issues for those who didn't follow
through with it. Which makes it a bad idea.