Ganked is a combination of Gang and Fucked, the term is widely used in the MMORPG community. meaning a gang of high levels got together and killed you.

To be killed without mercy on a MMORPG for the sport of it.

when one is gang-killed or attacked by many people unfairly in an mmorpg

to be pwned by multiple people at one time.
also can be used to describe rape

A situation or circumstance in which an individual is deceived, swindled or tricked out of monetary compensation.

when a big nibba destroys the word

to rape a person of their life without their consent in an MMOrpg
to kill/attack a person with risk to yourself in a Prison - especially when they are not looking

to avoid fairness , cause your to weak to win a fair fight