Gregory answers with two puns: "Ay, while you live, draw your neck out o' the collar" (1.1.4). He's saying that Sampson will not draw his sword, but draw his neck out of the hangman's collar (i.e., noose).
Gregory's point is that Sampson, despite his tough talk, isn't likely to do anything that will get him in trouble with the law. (Later in the scene we'll see that Gregory is right about Sampson.)