Did somebody thunk you in the head?
Just kidding. It's a good question. Allow for a generalized answer.
Personally, as one who appreciates dimension, I favor the use of colorful language, or at least within a context which grants of a certain license. Certainly not all do. So yes, as Mr. England cautions, the first rule of "proper usage" in this respect is certainly the exercise of sound judgment as to just how formal the context is. And, no doubt, by formal he means not intended as art.
In any venue of life, writing being no exception, the ability to think outside of the box is among the most appreciable of traits. And certainly the use of terms like thunk tend to fall into that classification. Art in particular though ---of which writing has long been king--- isn't mere or generic or even exceptional ability in the sense of cause and effect, but is rather demonstrable ability, the kind of ability which cannot help but show itself en route to its effect. This unavoidable fact invites of the scourge to any art from, to wit, vanity.
So, in my not always humble opinion, I should think that an approximation to rule number two, that is, toward your notion of proper usage. I almost wish I could say that your goal should be to make sure your creative expression never makes the reader think of you. But that, as I intend, would contradict everything I just said. It's unavoidably okay for the reader, at intervals, to think about you and/or your abilities as a writer. What's not okay is for that to be your leading objective as a writer... ever. The thoughtful reader can smell that. And it stinks. So sure, make use of all the "dimension" your mind can auto-generate, but only if it helps paint something other than a self-portrait. Foshizzle?