鑽牛角尖〔钻---〕 zyun¹ ngau⁴ gok³ zim¹ {zuān niú jiǎo jiān}

1. lit. to penetrate into a bull's horn (idiom); fig. to waste time on an insoluble or insignificant problem
2. to bash one's head against a brick wall
3. a wild goose chase
4. a blind alley
5. to split hairs