Dutch, short for: Je weet zelf(zelluf)
Common in the west of the Netherlands.
Meaning: You know. (lit: you know it yourself)
Mostly put at the end of a sentence.
Used to stress what has been said, or to put a sarcastic twist to it.
my life is awesome, JWZ.
I'm doing -insert something really cool-, my life is really hard, JWZ