Gank is a recurring phrase commonly used by Dean and Sam Winchester. It refers to them killing a monster.
After killing the Movie-Monsters Shapeshifter, Dean uses it to describe how the monsters get it in movies Monster Movie.
Dean used it to talk about killing the witch in It's the Great Pumpkin, Sam Winchester.
During The End, an Alternate Dean used the phrase as to why he shouldn't kill his counterpart. Dean said he'd only be hurting himself if he did.
Meg used it in Abandon All Hope... to mock Castiel on his lack of power.
Sam and Dean used it in 99 Problems, to refer to demons and Whore of Babylon.
In Caged Heat, Dean used it when he asked Sam about them previously killing demons but now work for them.
During Frontierland, Dean used it when he told the Deputy about Elias Finch while the latter was confused by the phrase.
In Mommy Dearest, Dean used it after seeing Eve on a camera footage and referring to his lack of knowing how to kill her.
In Season Seven, Time for a Wedding!, Becky used it after Guy reveals himself to be a Crossroad Demon and said if Sam knew what Guy was he'd "Gank your ass", something he agreed with.
After waking up in Purgatory in Survival of the Fittest, Dean used it after remembered the death of Dick Roman.
In What's Up, Tiger Mommy?, Dean used it when telling Castiel that they would defeat the Leviathans again.
During The Devil in the Details, Sam uses it to tell Lucifer that he won't let him possess him to defeat Amara since he'd start the Apocalypse again.
- It is a recurring phrase in the show.