Writers and speakers use humor to convey truth by using humorous comparisons and examples related to the conveyed truth<span>. The truth is never simple and not everyone understands the complexity and the true meaning of it. With this constraint, writers, and speakers use a more understandable explanation. They use examples and comparisons for helping the people to understand.</span>
<span>Cliché basically means you're or someone else is using an overused/worn down word/thought/idea/etc. It can </span><span>even get to the point of being trite or irritating.</span>
No they aren't proper to use in writing class they are considered slang. It would show your teacher that your not interested in sounding educated and proper.
Hope this helps!
