Food Bag Waterproof Barrier

Use animal feed bags anytime you need a waterproof barrier, like:

Under indoor plants so the water doesn't seep into the object it's sitting on
As a crib protector between the mattress and the sheets
As a drop cloth
Under messy kid paint projects
Under a sand box to make a barrier between the sand and the ground so weeds don't come up through

Can you think of other similar uses? Put them in the comments to share.