noun · A person who knows exactly what another person is thinking, often used in the idiom "肚子 dù​zi里 lǐ的 de蛔虫 huí​chóng".

你真是我肚子里的蛔虫，我想什么你都知道。

noun · A type of parasitic worm, especially Ascaris lumbricoides which infects humans.

他不讲卫生，肚子里长了蛔虫。