Beginning yesterday and running until Friday, Shake Shack is offering a special limited edition burger created by a different celebrity chef every day this week at its original Madison Square Park location. Here's the lowdown on each. While regular lines for burgers there are always lengthy, today Shake Shack tweeted that today's David Chang-created burger was their longest in history at over 400 people long. Which celebrity chef burger are you most likely to wait in line for? Vote below.