A programmable Human Interface Device (HID) emulates a USB mouse, keyboard and/or joystick. Although incredibly convenient time-savers, these devices can be dangerous in the wrong hands. Do not leave your programmable HID device unattended. An unattended HID device is essentially is the same as an unlocked workstation. Even if your workstation is locked, an unattended HID device can be subverted to attack your computer.
In addition, even if you do not have a programmable HID device, always inspect your computer before using it. Make sure all USB ports have only the expected devices attached. Someone else may have attached a programmable HID device to take over your computer.