I was shopping a local 99 cent only store on Saturday May 9, 2020 and noticed one of your employees stocking shelves and he was not wearing medical mask.He was blocking the isle with empty cardboard boxes. I tried to get through and said excuse, but he did not hear me because he was listening to music.When I asked him to put his mask he just looked at me and laughed at me and kept on doing his job. This a law and he should have known better. It took three store employees to make him understand the importance of wearing a mask. I walked by his isle twice and he just looked at me looking at me and laughing. This happened at 12:30 pm in the store on Imperial Ave in El Centro Ca.