Binder clips are endlessly useful to have around. One of their many uses is to attach trash bags to a trash can to avoid having the bags collapse in on themselves.
Oftentimes you might be able to stretch a bag around the top edge of the trash can to obtain the same effect, but this can put tension on the bag and lead to tears. Depending on the situation, it also may not be as secure over time.
It is possible to get away with only two binder clips, on opposite corners (as shown in the image above). Using as few as possible makes sense to save the time attaching and detaching them when swapping bags.
Keep in mind that you’ll need a trash can with a lip for this particular life hack to work.