"吐槽" is formed by combining the character 吐, meaning "to spit", with 槽, meaning "trough". Literally, this creates the image of spitting into a trough, but figuratively it has been adopted to express the act of humorously criticizing or mocking something, often by pointing out its flaws or absurdities. This specific meaning originated from Japanese comedic performance and was assimilated into Chinese usage.