She said the group arrived on Saturday afternoon and stayed for about an hour while smoking cigarettes and 'partying'.
'At one point she was just standing in a bikini,' the insider said. 'She wasn't in a good state, I can tell you that.'
http://www.dailymail.co.uk/news/article-5909787/Hard-partying-Malia-Obama-celebrates-20th-birthday-Montauk.html