I don't know if you've ever done this or not, but I have.
You know the oily flea and tick treatment that goes on your dog or cat in which you squeeze it and apply between the shoulder blades? Have you forgotten that you applied it and go to pet your sweet animal and receive an oily hand? If you tie a colorful ribbon onto their collar, it will serve as a reminder not to pet your animal in the shoulder area for a few hours.
One more thing, if you do get the medicine on your hands, it should go without saying, but I'll say it anyway, wash your hands thoroughly with soap and water.