The word واطي is used to mean low literally and figuratively. You can call someone low (i.e. lowdown good for nothing snake in the grass) just like you would in English, or you can use it to mean something like "lower your voice". In MSA منخفض is used to mean low. واطي is specific to Levantine dialect and isn't used at all in MSA.
1. هو واحد واطي (huwwi waahid waati) - He is a lowdown good for nothing double crossing snake in the grass.
2. وطّي صوتك (watti sootak) - Lower your voice.
I also have a question for anyone who can answer it. There's a Jordanian song sung by احمد الدرايسة (Ahmad-Al-Draysseh) that says حيطنا مش واطي واحنا اردنية. Does anyone know what حيط is?