Be Not Mad!
No, Be Not Mad is not a typo. Be Not Mad is a saying that means be any emotion but mad. Be happy, glad, or even sad. Sadness is an emotion and it is humane. Anger is not humane. Please be happy while on this site.
Don't Be Hatin' !
Hate is a strong word, so don't use it with something small like just because your friend didn't give you the answers to homework. You may think, "But isn't love a strong word?" Yes it is. So the same rules aply to it