Definition 1 of 1
A form of addressing a stranger, who is momentarily not facing you.
Although it is considered rude in some places, it is actually an acceptable way of calling out to passerby in certain scenarios.
"Schchoo! Where is bypass?" (Excuse me, can you help me with directions to the city bypass?)
"Schchoo! You left your flower bouquet"
'Schchoo! What are you looking at?"