My experience with USB Rubber Ducky

USB RUBBER Ducky is 

• Social engineering tool
• Keyboard looks like USB
• Because Human use keyboards , Computer trust humans
• Can run payloads (has simple scripting language) , key-logger , and other attacks
• Examples of Payloads https://github.com/hak5darren/USB-Rubber-Ducky/wiki/Payloads 
• Link to build the script https://ducktoolkit-411.rhcloud.com/Home.jsp
• I run the below safe script in my PC :)