When you want to express the idea of showing contempt or defiance towards someone or something, you can use a variety of synonyms for "thumb your nose at". One option is to say "shake one's fist at", which conveys a similar gesture of aggressive disregard. Another possibility is "snub", which suggests a deliberate act of disrespect or rejection. "Deride" is another synonym that suggests a mocking or scornful attitude, while "taunt" implies an intention to provoke or insult. Finally, "disregard" or "ignore" can convey a more passive sense of disregard, without the overtly confrontational tone of other alternatives.