lit. repair the plank road by day while secretly crossing the Wei River 渭河[Wei4 He2] at Chencang (idiom, refers to a stratagem used by Liu Bang 劉邦|刘邦[Liu2 Bang1] in 206 BC against Xiang Yu 項羽|项羽[Xiang4 Yu3] of Chu) / fig. to feign one thing while doing another / to cheat under cover of a diversion