The USB rubber ducky acts as a HID (keyboard) which naturally allows you to input keystrokes into a computer. Plenty of scripts on the github page allows commands to be run super fast. Will not work if computer is locked.
Works even if computer is locked. (evil)
PoisonTap produces a cascading effect by exploiting the existing trust in various mechanisms of a machine and network, including USB/Thunderbolt, DHCP, DNS, and HTTP, to produce a snowball effect of information exfiltration, network access and installation of semi-permanent backdoors.