A locked chest with secret content.
The content should have collectors value, so that keeping the secret adds value
The collectibles should be originally sealed and protected.
The longer the chest is locked, the more valuable the present becomes.
examples:
- sealed tradingcard booster packs
- sealed comics
- sealed albums
- collectible coins
Some of these items you will get for very little money.
If they are in good condition, they will eventually become quite valuable.
In case you want to be mean, or test somebody, you could also put in:
- nothing
Feel free to add examples for content below