Meaning/Usage: Used when you want to hear the truth
Explanation: "Straight" is referring to straightforward. When people had to tell someone bad news, they would try to find ways to make it sound less bad. To do so, it would require a lot more words and a lot of creativity. However, when people want to hear bad news, they don't want to hear something without additions made by the speaker. Therefore, it was common for the listener to be firm and tell the speaker to speak be straightforward and to speak the truth without adding things.
"Just give it to me straight, I can take the news."
"This is hard for me to say so I'm just going to give it to you straight."
"Just give it to me straight. How bad can it be?"
A. "I have your test results back."
B. "How bad is it? Just give it to me straight."
Other Common Sentences
"I will tell you honestly."
"I will tell you directly."