It's when you smoke out your homies and the moment the weed is gone, they leave.

Having a bailout plan when going on a blind date in case he or she is not what you expected and you do not want to spend the entire evening with them.

Thoughts that creep into your head expressing a desire to not attend an event that you previously agreed to attend.

The process of fucking a chick (rail), then leaving for something more fun (bail).

To corner somebody physically, to cut off their retreat. Australian slang.

That point toward the beginning of the criminal injustice loop when money is essentially extorted from folks who must pay the piper for a chance to go home.

the practise of metaphorically sowing one's seed and subsequently immediately departing from the scene as there is no further interest or motivation.
or...
the state of mind that you might adopt when looking at somebody when the attraction is preventing you from thinking about anything other than monking and bailing...