The Big Joe 5 is a Crossbow featured exclusively in Medal of Honor: Underground.
The Big Joe 5 is an instant-kill crossbow that must be reloaded after each shot. The reload takes an awfully long time, and ammunition for the crossbow is tremendously scarce, having only one ammo pickup in the entire single player campaign.
The Big Joe 5 is the starting weapon in the mission Wewelsburg: Dark Camelot, and is a selectable weapon in multiplayer. It is one of the few weapons that cannot be used to do a melee attack when its ammunition runs out.