My cat ate a ribbon?? Please help!!!?

Absolutely, call your vet to ask when it should pass. Did you have a sample of the ribbon to take to the vet? The reason I ask is that my beautiful tuxedo cat got into my knitting back in January, and ate some acrylic yarn. We took him to the vet, and they operated because the yarn had stretched out in his intestines, and because it was acrylic, it wasn't being affected by stomach acids or the digestive process. He survived the surgery, but died the next day from post-op complications. I wouldn't want anyone else to go through that.