Some guys reserve flip-flops for the water. Others keep them on from April to September. It’s best to find a middle ground based on your work setting, and the degree to which your toes resemble eagles’ talons. For what it’s worth, there is an increasingly vocal constituency calling for men to take the footwear highroad in the warmer months. But, for better or worse, all Saturday, Old Navy is selling flip-flops for $1.