Mistaken for a Student

Yesterday, I was running late and entered my classroom wearing a hoodie that had a name tag from another building attached to it. My students burst into laughter as soon as they saw it. One even shouted out the correct class schedule before realizing their mistake. As I took off the hoodie, some tried to stifle their giggles while others openly mocked me for being confused about which room was mine. It's a rare occurrence that my authority is undermined so casually by an item of clothing. How do you maintain your composure when such situations happen?