むり, むだ, and だめ, for when something's probably not a good idea

So, how about some vaguely related can't/shouldn't words?

無理 (muri), also written むり or ムリ

Though it's sometimes translated as "impossible", calling something muri doesn't necessarily mean that it's outright impossible, nor that it's necessarily wrong as such. Such an action does, however, go beyond the limits of what is normal, acceptable, or sensible.

Junk science that needs to desist

Sometimes it seems like we, as a people, are incapable of discussing anything rationally, and it always seems to get worse when the discussion involves those who are in some way different from the majority. Heated accusations are frequently thrown around whether or not they have any basis in fact, or even make sense at all. And even when claims come across as calmer and more reasonable, they often end up being widely shared with little thought given to their accuracy or relevance.