Secret Codes of Samsung include the android secret code of Samsung.
Secret Codes of Samsung include:

Best Samsung codes
Network
GPS
Bluetooth
WLAN test
Firmware version information
factory tests PDA
display the IMEI number
Super Mode
Service Menu
factory reset
sim lock
Unlock any device
sim unlock
Phone information
Battery information
Wifi information
Battery history
Usage statistics Check Update
Reset Device
Unlock the device
Recover Forgotten pattern
Engineering mode
GPS test mode
Touch Test
Screen Test
Test Device is original or copy
check battery timing
Machine information
Software Information
Hardware Information
Test Photograph RGB and much more.

Some code of them may not work on specific devices but you can still try them because their manufacturer does not allow them. You can copy and share it with your friends.
After execute these hash code your device might be affected. So keep backup your important data before execute hash code.
Note: This is not official Application of Samsung.