Bobblehead - Luck is a Fallout 3 item, a Vault Boy Bobblehead. It permanently improves the Lone Wanderer's Luck by 1, up to a maximum of 10.
Location
The bobblehead can be found in the basement of Arlington House at Arlington Cemetery on a shelf. The cemetery can be reached via the Arlington/Wasteland Metro. The world map waypoint is named "Flooded Metro" and is located near Wilhelm's Wharf.
Behind the scenes
This bobblehead holds a four leaf clover in its right hand; these are popularly considered to be lucky.