The man on the left asks the man on the right how his “new project” is going. It turns out that the project is a secret, and the man on the right uses the clichéd statement, “I could tell you, but then I’d have to kill you.” This causes the two men to laugh.
The man on the right (with the secret project) then corrects his previous statement by updating “kill you” to “kill you even sooner.” What this means is that the man on the right’s “secret project” was actually to kill a series of people, including the man on the left. By divulging this secret, he would be forced to kill the inquiring man earlier than scheduled, hence the addition of “sooner.”
