Much like the McRib, the Shake Shack corn dog remains enigmatic, popping up only sporadically, at the times when its creators deem us worthy. Well, this weekend is one of those times! Danny Meyer & Co. will commemorate Memorial Day by offering it, along with corn relish from Rick’s Picks, for $4.50. The caveats: It’ll only be available today through Monday, and it will only be available at the Upper West Side Shack location. Get to it!