Stable prepack / stand stable liquid prepack

In many countries such as china, plastic bags are used as containers for liquid food like milk. This type of containers can be ripped open on one side conveniently. However an opened bag like this with half of the milk left in it can easily tip over and cause a spill if left unattended without support.
By adding a strip of tape on its bottom, the bag can be folded up in one corner, which forms a flat surface to be placed securely, avoiding hazard of spill.