Lock the box with your lock and send it to your friend.
Let him lock the lock again with his lock.( as it was mentioned that the locking ring is more than large enough to have a lock attached.)
and send it back to you.
You remove your lock with your key, and send it back to your friend.
he opens his own lock with his key and Voila.. gets the valuable object..
1.Air conditioner.. As it gets hotter.. It gets cooler..
2. Chalkboard or blackboard
4.A woodchuck would chuck as much wood as a woodchuck could chuck if a woodchuck could chuck wood.
5.Memory or age
6.All the money i can get
7.Whatever time your clock says.. it's only gonna come once a day..