There's a lot of filthy junk online — kids shouldn't see too much of it.
Tips
usage
Used both for literal physical mess and for morally dirty/obscene content. A close cousin of 乱七八糟 (luànqībāzāo) — same '七八' chaos pattern, but 乌 (black/dark) adds a sleazy or filthy connotation that 乱 (chaotic) lacks.
memory
Think 'a black 七八 (7-8) mess' — 七 and 八 in Chinese idioms often signal 'all over the place' (cf. 七上八下, 七嘴八舌). Add 乌 (black/dirty) and you get the grimy version of chaos.
