A piece of broken glass!? What can't you do with it is a better question. You can hold it in a trembling hand, jaw twitching, and threaten to cut people, you could actually cut said people with said piece of broken glass, you could stick it in your dinner at a fancy restaraunt and demand a refund, you could find the object it came from and cry that said object is broken, you could glue it to a hat as a festive decoration for St. Jegnamohire's day, or you could put it in a jar of lemon juice and tell people NEVER to TOUCH it. It's up to you!!