expression
the pot calling the kettle black
Idiomatic expression criticizing someone for pointing out a flaw in another that they themselves have; literally 'eye goop laughing at nose snot'.
彼が私の遅刻を注意するなんて、目くそ鼻くそを笑うようなものだ。
Him scolding me for being late is like the pot calling the kettle black.
自分のミスを棚に上げて他人を批判するのは、まさに目くそ鼻くそを笑うだ。
Ignoring your own mistakes and criticizing others is exactly the pot calling the kettle black.
Both express the idea that two parties are equally flawed, but 目くそ鼻くそを笑う specifically highlights the hypocrisy of one party criticizing the other, while 五十歩百歩 simply states they are essentially the same.
A proverbial expression of uncertain origin, literally comparing eye discharge (目くそ) laughing at nasal mucus (鼻くそ), both being similarly unpleasant bodily substances.