Fight gravity.
Don't be afraid of spilling drinks anymore.
Watch the video to see the wonder.

One:
http://www.youtube.com/watch?v=jBTKmu8FVIg

Three:
http://www.youtube.com/watch?v=W83O7gRDyN8

Four:
http://www.youtube.com/watch?v=tn49A9DKy0U

Cut three strings of equal lenght.
Tie the strings to the rings.
Tie the strings together on top making sure they end up with the same lenght.

TIP: make sure you don't hit anything with the cup else it will spill.

One cup:
http://www.youtube.com/watch?v=jBTKmu8FVIg

Three cups:
http://www.youtube.com/watch?v=W83O7gRDyN8

Four cups:
http://www.youtube.com/watch?v=tn49A9DKy0U&feature=youtu.be