It can be used two ways:
1. Getting lucky, or gaining much through an action
2. Leaving a location
1. What a floss out!
2. Ok guys I'm flossin out cya later
(v.) the action of not showing up or deciding not go to a previously planned event at last minute's notice.
"He was suppose to go with me to the movies, but he flossed out. Lame!"
"Don't floss out! I need you to be there."