cattle prod

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

• noun A usually electrified prod designed for driving cattle.

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

• noun A stick designed to goad cows, steers, and similar animals in order to prompt them to move in a desired direction, now usually electrified to administer a stimulating shock to the animal.
• noun figuratively Something used to goad or push someone to act.