cock-and-bull story
noun [ C ] informal disapproving uk/ˌkɒk.ən.bʊl ˈstɔː.ri/ us/ˌkɑːk.ən.bʊl ˈstɔːr.i/
（尤指用作借口的）荒诞的故事;无稽之谈
a story that is obviously not true, especially one given as an excuse
He gave me some cock-and-bull story about having to be at his cousin's engagement party. 他对我说他得去参加表兄的订婚宴，这显然是信口胡诌。