A pig stick is a staff that carries a flag

Flag

A flag is a piece of fabric with a distinctive design that is usually rectangular and used as a symbol, as a signaling device, or decoration. The term flag is also used to refer to the graphic design employed by a flag, or to its depiction in another medium.The first flags were used to assist...

 or pennant

Pennon

A pennon was one of the principal three varieties of flags carried during the Middle Ages . Pennoncells and streamers or pendants are considered as minor varieties of this style of flag. The pennon is a flag resembling the guidon in shape, but only half the size...

, usually the burgee

Burgee

A burgee is a distinguishing flag, regardless of its shape, of a recreational boating organization.-Etiquette:Yacht clubs and their members may fly their club's burgee while underway and at anchor, day or night, but not while racing. Sailing vessels may fly the burgee from the main masthead or from...

 of the boat owner's yacht club, above a mast

Mast (sailing)

The mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...

 of a sailboat

Sailboat

A sailboat or sailing boat is a boat propelled partly or entirely by sails. The term covers a variety of boats, larger than small vessels such as sailboards and smaller than sailing ships, but distinctions in the size are not strictly defined and what constitutes a sailing ship, sailboat, or a...

. It's connected to a halyard

Halyard

In sailing, a halyard or halliard is a line that is used to hoist a sail, a flag or a yard. The term halyard comes from the phrase, 'to haul yards'...

 so when it's raised the top of the mast, the "pig stick" extends above the mast, allowing the flag to be seen flying above the boat's sails. Pig sticks are especially useful on catboats

Catboat

A catboat , or a cat-rigged sailboat, is a sailing vessel characterized by a single mast carried well forward ....

and other sailboats which have no stays to which a flag halyard can be attached.