There is an easy possibility to share caches between users of c:geo if both devices support near field communication(NFC):

Make sure NFC is enabled on both devices. Then just open the cache details of a cache on one device and place it back to back with the second device. The first device should now show a reduced size c:geo window, which you now click on to send the content to the second device.This will automatically start c:geo and show the same cache on the second device. If c:geo is not installed on the second device, it will offer the installation of c:geo.