This Man was one of Bree Van de Kamp's many sexual conquests during her alcohol addiction.
We see Bree outside her house, making out with a random man. As two neighbors walk by, they give them a disgusted look, discomforting the man. He suggests moving inside the house, but Bree disagrees, ignoring the opinion of the neighbors. They both then start to kiss once more. ("What's the Good of Being Good?")