Using Figurative Language with Sign
Many people have asked how to sign things that say one thing but mean something else. This happens a lot in the English Language!
Some Examples: It's raining cats and dogs!, or You look really sharp today.
Now as native users of the English language, we know that neither cats or dogs are falling from the skies .nor is the person in the second sentence looking rather pointed. These are concepts that people who are learning English as a second language also struggle with, yet we find phrases like these used in everyday language all the time. The thing for you to focus on as a signer is the main idea of what is being said and then sign it conceptually correct.
It's raining cats and dogs = It's really raining hard
Even with this example you would NOT sign that it is raining HARD (as in the opposite of soft). You would sign RAIN + A LOT or RAIN+RAIN+RAIN (with a facial expression showing a lot).
You look really sharp today = You look really nice today.
You would sign it like this.
Now, with that said, as a former teacher, I would think that it is important for my students to know what someone was saying when they used figurative language (whether it was being said live or they are reading it in a book, and it is actually fun to see my students use it in their everyday use of language). So I would sign it conceptually correct first but then TEACH them the way it is used in figurative language and sign it back and forth interchangeably so that it becomes part of the student's vocabulary.