First you need to find a broken adapter I used a cheap adapter for this project. You can find these cheap china made adapters on ebay under a dollar. Look for a label sticker there is usually a screw under it.
Remove the screw and take out the Chip. You can keep the chip if you want to for some other project or just throw it away.
Cover the metal contacts with some electric tape so that if someone plugs it in whatever you are hiding does not get damaged. (optional) You can remove the female end of the usb and cover up the opening.
Close the housing back up and put the screw cover it with a label if you want to.
You can hide anything inside. A usb containing the password to launch the nukes,cash,microphone. ://
The possibilities are endless.