A polite way to tell someone to fuck off and die because that person has created the circumstance between you and them which makes you care less if you ever see them again.
He could not deal with her bullshit and destructiveness in their relationship, so he signed the letter "have a nice life."
by Cravon Moorehead November 25, 2017
(Idiom.) What is said to someone after ruining thier life or leaving them to ruin it themselves.
I got your wife, have a nice life!
by KuNg-fu jeSUS May 6, 2004
It basically means goodbye forever. If you say this to another individual, you are telling them, from now on, from this moment on, you couldn't care less what happens to them, as long as you never see, or hear from them again. You are banishing them from your circle of loved ones and friends, from your life. It is almost always justified/warranted.
"Don't worry about responding to this. I just wanted you to know how I felt. Have a nice life."
by BlueMoon1 August 16, 2021
Another way to say the word Farewell. Used when you just might never see the same person ever again.
Boy: I'm moving to New York for my job. So we might never get to see each other anymore.

Boy #2: It's been fun knowing you bro. "Have A Nice Life."
by AMysteryA April 25, 2015