An actor or ordinary person that is in a movie, but does not receive any credit for being in it, is said to make ‘a cameo appearance’ in the movie. In life, it can be said that someone made a ‘cameo appearance’ if they attended an event where they were not expected. “I made a cameo appearance at my neighbor’s good-bye party.”
不請自來
在電影中，這句話是指客串演出；日常生活中，可用來形容某人並無受邀卻自行出席某個場合。例句：「我在鄰居的餞別派對上不請自來了。」