I hit my husband on the arm once, when we first started dating. I grew up with a brother, so there was always playful smacking. He told me he really hated that and asked me not to do it. I never did it again. We talked about it recently, and he said it was because he was afraid he'd hit me back as a knee jerk reaction, which I understood. Just someone asking you not to do something was enough for me to stop. Why would I do something they didn't like?