A term used to describe someone who doesn't follow through with plans, or bails on them.
"I was supposed to hang out with Willie today but he bailed again. What do you expect, he's hay."
As originated on The Simpsons, Gimbles is used to describe someone or something who has been fired, quit, or in general is just gone.
Agnes: Gimbels is gone, Marge, long gone. You're Gimbels.
Reece: Where's the beer?
Kenny: I asked Willie to pick it up since he works right beside the beer store, but he didn't want to.
Reece: Oh so Willie's Gimbles.