If someone tells a joke it's polite to laugh.
Anne's boss, who has to fill a manager position, is talking to her at her lunch break, and he makes a dumb joke.
Anne wants to get back to work.
Anne laughs at the joke, then says that she needs to get back to work.
Anne ignores the joke and tells her boss she needs to get back to work.
Her boss finds her friendly, and she later gets a promotion to manager.
Anne's boss sees her as not people-friendly and passes her over for promotion to manager.