"Ching chong" and "ching chang chong" are racist pejorative terms sometimes used in English to mock the Chinese language (and sometimes other languages of Asia), people of Chinese ancestry, or other people of East or Southeast Asian descent perceived to be Chinese.
That's rude, at least I never use those words. But people need to stop using those words because they are really rude. One of my classmates used that words and I didn't like that.