Question: What is the meaning of, "The clown shall make those laugh,
whose lungs are tickle o' the sere"?
Answer: "The clown shall makes those laugh whose lungs are tickle o' the sere." The seare, or sere, was part of or attached to the trigger of old matchlock guns, so arranged that the slightest movement would make the gun discharge. Lungs, then, "tickle
o' the sere," are those easily excited to laughter.
Mertins, Emma. Shakespeare Examinations. Ed. William Taylor Thom, M. A. Boston: Ginn and Co., 1888. Shakespeare Online. 10 Aug. 2010. (date when you accessed the information) < http://www.shakespeare-online.com/plays/hamlet/examq/five.html >.