I wasn't offended, it didn't make me mad, I just laughed.
One of the regulars who never wants to leave the floor until everyone else has, kept talking loudly. At first, I thought he was talking to someone, that is until I walked toward him. He looked my way as I got closer to him and I (in typical librarian fashion,) placed my index fingers over my lips.
The patron lowered his voice, but he kept talking. I was fine with that.........until, five minutes had passed and he was back to talking loudly. I got up once again to go over to him, he saw me and got quiet. Five more minutes passed, once again, he begain to get louder and louder. My boss said, "Just call security." I told my boss not to call security, because I thought the guy would lower his voice. He turned, saw us talking, and quieted once again. Five more minutes passed and he got loud. I got up, he looked at me and I placed my fingers over my lips. This time, dude mean mugged me, turned around, picked up his belongings and left.