Workshop mode is perfect for this situation. To turn it on, use the Workshop Mode toggle on the Login or Settings screen. When this mode is on, all of your data on the device is removed when you log out and pass the device to a friend. Logout can also be triggered automatically when:
the app is sent to the background AND you don’t resume using it within 10 minutes; OR
the smartphone is locked AND you don’t resume using the app within 10 minutes.