ooossshhhh
When someone does something that is unnecessary or uncalled for.  
If Rachael brought back In-n-Out for her friends and when she returned she took a digger on the top step and split all the food onto the haz-mat floor, the group would say ooossshhhh. The first reason is because reckless Rachael dropped the food they were suppose to eat, and due to the fact clumsy Rachael took a nasty spill. 

If Rachael spills my $15 whiskey on the rocks at the club!