This Upanishad belongs to the Atharva Veda. As the name of the Upanishad suggests, the teachings revealed in it are such as to leave its students clean, like a shaven head (mundaka), rid of the veil of ignorance. The lucid translation of the text along with Shankaracharya's commentary on it is an additional aid to comprehend the profundity of the subject.
Avoid excessive merriment. A mind in that state never becomes calm; it becomes fickle. Excessive merriment will always be followed by sorrow. Tears and laughter are near kin. People so often run from one extreme to the other.
-Swami Vivekananda