Question: Here's the scenario: I screwed something and that caused some real harm. Now another person could just tell me, “Dude, you screwed X and this caused this and this harm," but instead he will try to be supe- diplomatic and vague to “not hurt my feelings.”

I’d like to tell him, “Dude, stop that diplomacy and prettification — I can take the ugly truth, whatever it is.”

Is there a widely recognized idiom for conveying that message?

Answer: 
"Tell (or Give) it to me straight".
* **Be honest.**

Or, a little less tersely:

* **Be honest with me.**