What's the Joke?

This photo was snapped at the now infamous demonstration for Ilan Halimi on February 26. It shows former socialist Prime Minister Lionel Jospin on the left, with the current head of the Socialist Party François Hollande in the center, and the socialist mayor of Paris Bertrand Delanoë on the right. While we don't think it's fair to accuse them, without knowing precisely what the joke was, the picture is still an excellent symbol of the farce that this rally turned into. The patriotic/nationalist websites spared no effort in condemning the trio.