口福 belongs to a small family of Chinese "luck" words built on
福 (good fortune):
口福 (food luck),
眼福 (yǎnfú, treat for the eyes — seeing something rare),
耳福 (ěrfú, treat for the ears — hearing something good). Saying
你真有口福 is a warm host's compliment: "how lucky you are to be eating this." The fixed phrase
大饱口福 = "to feast to the fullest."
