One of the challenges in space is to eat and drink, due to the absence of gravity. This makes sometimes the food floats, or it is necessary to use a special food bag for the eating or drinking process.
Interestingly, like various experiments in space, NASA also did a number of designs involving cups for use in space, and recently demonstrated the use of the space cup.
NASA stated that the design of the cup uses the advantages of fluid dynamics in giving an effect similar to gravity, while allowing astronauts to sip water from the cup. The water also stays in the cup, and does not float out.
NASA succeeded in this through the concept of surface tension and also the geometry of the cup itself. When the astronaut puts the cup in the mouth, the water will be automatically attracted to the astronaut's mouth by capillary diffusion.
In addition to use in space, NASA is also looking at using the same concept in various devices, including medicine on Earth.