1.) To steal, pilfer, and/or obtain without permission
2.) To injure someone intentionally, for whatever reason
Note: Can also be spoken aloud during the process of Ganking.
"That motherfucker just Ganked my shit!"
"I'ma Gank this sonofabitch!"
"Bitch, you been Ganked!" or, in the process, "Hey, is that your beer? Gank!"