Most people have been in the kitchen and suddenly realized that their kitchen knife was a bit on the dull side. However, not everyone has a sharpening stone lying around and even if you do, it can take a second to fully sharpen a knife. Luckily, you can use ceramic cups to quickly sharpen knives and scissors that have gone dull. Just make sure to use the bottom ring where there is no glazed finish.
The ceramic should quickly sharpen edges in a pinch. However, it's always advised that you invest in an actually sharpening stone for future use as it's easier on your blades.