Idiomatic mistakes

[karynmadam]

What do you call the act of using the wrong words in an idiomatic expression, such as "the straight and skinny" instead of "the straight and narrow" It is neither malapropism nor neologism... but there should be a term...

[chester_100]

What do you call the act of using the wrong words in an idiomatic expression, such as "the straight and skinny" instead of "the straight and narrow" It is neither malapropism nor neologism... but there should be a term...

In your example, the collocational content of the expression has been violated. In EA, that phenomenon falls under the category of Lexico-Semantic Errors.

We can call it Pragmatic Deviation.