When a backup generator at Old Homestead Steakhouse sputtered, the restaurant started serving hundreds of pounds of steaks, burgers, lobster tails and shrimp on the street outside for downtown denizens. David Blaine, the modern-day Harry Houdini who spent days recently being shocked in a steel suit, pitched in to provide spontaneous street entertainment. “David was rumbling by on his motorcycle, and he stopped to see why there was a line on 14th Street,” said a spy, adding 800 chowed down. Blaine then asked restaurant co-owner Greg Sherry if there was a deck of cards in the house (luckily, some waiters must play poker on breaks). Blaine used the full deck and some spare silverware to perform magic tricks outside for an hour and a half. The magic man, an Old Homestead regular, was offered a doggie bag but said he’s on a special diet in preparation for his next stunt. Further along the meat trail uptown, Benjamin Steakhouse told us yesterday that through the weekend it’ll donate 10 percent of its tabs to the Red Cross to help those affected by the storm.