"Mkhallfo w Nessee?" is an expression which literally means "Did I give birth to him and forget all about him?", metaphorically, it is a Lebanese slang expression, which metaphorically means "I do not have to do him any favors".
Sample conversation:
Person 1: "why did you not help him pass his exam"
Person 2: "i barely know the guy, shoo mkhallfo w nessee ana?"
Jeet w' Allah jebak - جيت وألله جابك : Lebanese Slang, of unknown origin. Meaning:"You came and God brought you". This phrase denotes the relief of someone about the timely arrival of a 2nd person in order to help solving a situation.