Braised eggs are a common food, usually cooked eggs are coated with soy sauce or salt and then cooked by heating. The performance of Tu Lingzhu in the play is described as a marinated egg, and this contrast may cause laughter from the audience.
In addition, the shape and design of the earth spirit beads may also arouse a certain sense of humor. For example, it may be designed with some funny features, such as different sizes, uneven colors, rough surface, etc., which may make people feel interesting and funny.
Generally speaking, the reason why the earth spirit bead is funny may be because its image and metaphor make people feel relaxed and happy, which leads to laughter.