I have heard that they are "merrymaking and lovemaking" the entire time. But if there is someone more familiar with the lives of fairies, I would love to learn about their culture...at least some sources about it.
Check out: Fairy Legends and Traditions of the South of Ireland by Thomas Crofton Croker http://www.gutenberg.org/ebooks/39752
The Brothers Grimm translated Crokers Fairy Legends and provided a summary in the beginning of their translation. Below is what they said, loosely translated and paraphrased:
Fairies always live in large groups, never alone or in pairs. They are invisible to humans. Their houses are in rock cracks, caves and old giant hills. They love music. They celebrate under roomy mushrooms. They disappear at first light. They love to play ball, which they play with great eagerness, sometimes they come into dispute when playing.
There is of course much more.
See also: Lays and Legends of the North of Ireland by Cruck-a-leaghan, Slieve Gallion.