1) used when a friend is having a tough time or seems to have a lot on their plate to make them laugh off their stress and to show them that you know they can do it.
2) a phrase that closely resembles the usage of don't die
and the meaning of man up
or buck up
3) used less for mocking and more for inspiration/consolation
Friend A: "I can't believe I have an 8-10 page paper, two tests, and a 10 minute presentation all in one week."
Friend B: "Don't cry."
Friend A: "Thanks man, your tender words will help get me through it."