It kind of bothers me as a Buddhist when people use "Zen" as an adjective to decribe serenity and peace, because originally Zen is the name of a sect of Japanese Buddhism, so seeing Westerners use the word like that is kind of like seeing other foreigners use "Protestant" to describe, oh I don't know, hot temperatures, "Catholic" to describe slippery-ness, or "Sunni" to describe rigidness and hardness.