I don't know if the phrase: "tire-toi" is a slang.

However, 'tire' is a conjugation of the verb tirer

You can conjugate it at this link: http://conjugator.reverso.net/conjugation-french-verb-tire.html

Tirer means 'to pull' , 'to draw' and sometimes means 'to take'

example: Tire la porte!

Pull the door!

So, literally it may have meant: 'pull out and get out of here' in the context of that movie's scene.

Hope someone will correct me if I am wrong.

I heard it:

tire-toi !!

Meaning: Go away.