What do you do if you're a woolies/coles customer and see someone blatantly stealing stuff?

I personally just looked at the customer and smiled uncontrollably, this is common amongst my culture when we see somebody cheating the system, we smile in an embarrassing situation, or diffuse it. Coles couldn't pay me enough to put my life on the line just because of shrinkage being responsible for my groceries costing more, the more people get away with this stuff.