Two years ago, I marked it on my card. I had been out bike-riding along country roads in eastern France. My friend & I stopped to say hello to some horses. I rubbed the nose of one as a friendly gesture. We got back on our bikes a few minutes later. That was it. I told this story to the CBP agent who read my card, when he asked about it. He kind of looked at me like "Why did you even report that?", chuckled, and sent me on my merry way.