Decorations: Make treasure map invitations rolled up like scrolls. Decorate everything in black and yellow. Scatter gold coins along the table. Make your own pirate flags out of posters or pillowcases. Hang them around the room or sew them together to make the plundering table cloth.
Food: Have a plundering table full of finger foods: sandwiches, chips, fruits, vegetables, pizza, red punch, etc. Serve everything on golden (yellow) plates. In the middle of the table have a treasure chest of assorted cookies for dessert. You could have sushi for adults.
Games:
Make & decorate paper hats & cardboard swords.
Pick out pirate names/ titles and make name tags.
Have a treasure hunt.
Make a treasure chest pinata.
Dance like a pirate - singing pirate songs.
Pin the Eye Patch on the Pirate (or parrot on the pirate, or flag on the pirate ship, ect.)
Play Musical Islands ( Like musical chairs, only use a piece of paper in place of the chairs.)
Sleeping Pirate: All the children (except one - The Pirate) sit cross legged on the floor in a circle. The pirate sits blind-folded, cross-legged in the middle of the circle with a large bunch of keys (or gold coins) on the floor in front of him. A child is nominated to creep up and take the keys and then return to their place without the pirate hearing them. The Pirate has three goes to point to where he thinks the raider is. If he is successful, the raider becomes the Pirate and the game continues.
