Ever on the go and forget containers for the kids snacks? Happens to me all the time. I knot handkerchiefs, cup napkins... but they always spill. Especially in the car. So I adapted this origami technique for a sturdy little cup. I use whatever clean-ish paper is around. It works with squares or rectangles.
Fold paper in half diagonally.
Fold the two corners in so they overlap.
Fold the front top corner down. (can fold back corner back, but I find this easier to pass around)
Fold bottom corners in for a standing base.
Fill with snack.