By / / This Saturday at 10 A.M. CP+B will unveil a giant ice block filled with Old Navy flip flops in Union Square. They will then wait for the block to melt before handing out the encased flip flops. With the predicted high temperature in the upper 70s, that may take a while. The stunt is part of CP+B’s “RSVP For Everything” Summer campaign for Old Navy. It should be pretty cool.