This pose is a variation of Half Lord of the Fishes, the Sanskrit name is Ardha Matsyendrasana, probably two of the most useless pose names ever. This pose helps stimulate your kidneys and your liver, in a positive way of course, and it's super easy to do.
Here's a helpful tutorial from Yoga Journal on how to do this pose, although I bet you could figure it out on your own. I do this pose almost everyday and anytime I'm bored while sitting at the airport.