I came very close to that last night at a friend's 50th Birthday party. I had taken the cake as a gift. My husband and I were standing beside it when a 50+ year old woman walked up to the table. While she was complimenting the cake, her right hand and finger were slowly moving toward the cake. Just as I was going to say something, she slowly began to withdraw it. Then as soon as her hand returned to her, she slowly began to move it back toward the cake. I knew she wanted to stick her finger in the cake or touch one of the gold stars on the front. I started to say something a second time and she slowly moved her hand back. She had continued talking to us the entire time. If I had not been standing there, I have no doubt she would have damaged the cake.
After she walked off, I looked at my husband and commented on her odd behavior. He had to agree that it was a really strange moment to witness.