What is Ventilate?
1.
Transitive verb: To shoot someone, with the implication that the holes made in the body would allow wind to pass through. May also be applicable to stabbing. Attributed to Kirk Douglas's character Cactus Jack in the 1979 film, "The Villain."
It is likely that no one has ever used this term seriously. It is usually heard as a humorous mock-threat between friends.
Cactus Jack: Take another step and I'll ventilate you!
2.
to shoot someone (from the notion of letting air into someone)
For a second I thought he was going to ventilate.
See