Plead the fifth

Explanation:
This is slang, it's very vivid and colorful if we can make good use of it.
It originated from the Fifth Amendment of the constitution, the main content of the amendment endow citizen with the right to plead for the guilty, so there is no need to provide evidence to demonstrate you're guilty.
And now it is so popular to apply in reality to express your refusion when was interviewed awkward or embarrassing question.

Example:
I heard you were very drunk at the bar last night? ---Well, I have to plead the fifth on this one.

Diary:
Yesterday is a hot day and I stayed at home, the biggest harvest was that I found a girl from B-web who did a great job on how to organize her ideas from logic. What's more attractive was that she was also a fan of reading. I enjoyed making friends who share the same hobby of reading. Even though she was young, there was great potential for me to learn from her.