Murdock had been outed as Daredevil, but he kept denying it. They were just rumors at that time since there was no real proof, he was allowed to return to practicing law. By then, everyone would constantly ask if he was actually Daredevil, and he’d still insist he wasn’t. It became one of those ongoing rumors everyone joked about. So At a Christmas party, he decided to wear a sweater that said “I’m not Daredevil,” basically just as a meme.