You would use the term when you think it would be in the be in the best interest of the party/s or person/s confronting you to leave and/or leave you alone. It should be stated with feeling.
You best step-off, mother fucker!
by W. Steward April 20, 2004
Can you define these popular missing words?
back away from a confrontation.
by Mr. Terrence L. Trezvant October 05, 2003