黄 (yellow) is Chinese internet/legal slang for pornography — likely from the early-20th-century use of
黄色 ("yellow") for tabloid/lurid content, mirroring Western "yellow journalism".
扫黄 is a stock political phrase in PRC media, often paired with
打非 (dǎfēi, "strike against illegal publications") as
扫黄打非.
