Term for blowing a spy's cover and used it to escape, dodge or evade the truth.
Named after Joseph Allen, who Vladimir Makarov iced after he does the massacre on an airport named after his master, in No Russian.
Underling: There's a rat on us.
Boss: Everyone, I'm Exposing a Joseph Allen on our group. *Shoots the underling* There, everybody knows that we never tolerate snakes on our group.