"Shashma" is a word used in old Lebanese colloquial to mean "bathroom", probably inherited from the days of the Ottoman rule in Lebanon. The word is still used by some old people.
Lebanese Slang. In English: "It puts tension on the nerves". Used to describe a feeling of stress. e.g.: - "I submited a new slang on slangmania.com several weeks ago and they havent posted it yet! Chi bi wattir el a3sab ya man!"