As DMK chief M Karunanidhi turned 94 today, his birthday party served as a gathering for more than one cause. While his party marked the occasion to celebrate his sixty years of being a legislator without losing a single election, the birthday bash was also a show of unity among an otherwise fragmented opposition ahead of the Presidential election. Not surprisingly, the ruling BJP that was not on the invitee list was the favourite punching bag. But the clearest unity call came from the Trinamool Congress' Derek O'Brien and the National Conference's Omar Abdullah.