pinking shears

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun plural Shears with notched blades, used to finish edges of cloth with a zigzag cut for decoration or to prevent raveling or fraying.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun sewing A pair of scissors with zigzag cutting edges, used to cut fabric: the zigzag edge helps keep the fabric from fraying.