noun
unreasonable demand; impossible request
Refers to a demand or request that is clearly unreasonable, excessive, or impossible to fulfill. Often used when someone is being asked to do something beyond reason.
上司に無理難題を押し付けられて困っている。
I'm in trouble because my boss is forcing unreasonable demands on me.
そんな無理難題を言われても、できるわけがない。
Even if you make such an impossible request, there's no way I can do it.