Probably the weirdest exit salutation in common use in Hebrew today. Yallah (or, more properly, ya'allah) is literally oh God in Arabic, but in the Hebrew vernacular has come to mean let's go or get on with it, a meaning close to its meaning in (Palestinian) demotic Arabic. Bye is the English word, used in the same sense in the Hebrew vernacular. So both words are not Hebrew, but this particular combination could only arise in Israeli Hebrew!
I've not heard yallah ciao. Yet.