I'm more than a bird, I'm more than a plane, more than some pretty face beside a train

Yesterday one of my co-workers was walking down the hall in our building while looking down at a piece of paper in her hand. Of course, since she was distracted, I couldn't let the opportunity pass. I ran up and startled her by acting like I was going to slap her.

After her initial reaction of jumping back, she elbowed me in the stomach. Luckily, I saw it coming and had time to flex my stomach muscles and avoid having the wind knocked out of me. She wasn't quite so lucky. She hurt her elbow.

She looked at her elbow, then at my stomach, and said with a tone of shock in her voice, "You have stomach muscles!?"