入乡随俗 = rùxiāngsuísú = "When you enter a village, you should follow its customs" This is an anciet chinese idiom. It's like "When in Rome, do as the Romans do".
食言而肥--break one's word 食means eat in acient time. 言 means language, words or speaking. 而 mean then,肥 means fat. someone eats his own words then getting fat.