From TibiaWiki

Party items were implemented for Tibia's 10th anniversary and most of them could be found in surprise bags looted from many different creatures. Since then, several NPCs that sell some of those items are introduced from time to time.

Party Items

Name		Attributes	Weight	Dropped By
Bag (Common Costume)		Temporarily gives you another costume	8.00	None.
Bag (Deluxe Costume)		Temporarily gives you another costume.	8.00	None.
Bag (Uncommon Costume)		Temporarily gives you another costume.	8.00	None.
Bar of Chocolate		edible	0.10	Nightmare Scion, Undead Jester
Cake		edible	5.00	None.
Candy		stackable, edible	0.05	The Mutated Pumpkin
Candy Cane		stackable, edible	0.50	Grynch Clan Goblin
Cookie		stackable, edible	0.10	Witch, Cave Rat, Munster, Grynch Clan Goblin.
Cream Cake		edible	5.00	Grynch Clan Goblin, Mad Scientist.
Decorated Cake		edible	6.00	None.
Fireworks Rocket		Explodes when used.	1.00	None.
Green Balloon		Can be hung on walls.	0.10	None.
Lump of Cake Dough		stackable	1.00	Grynch Clan Goblin
Party Cake		None	7.00	None.
Party Hat		Arm: 1	7.50	None.
Party Trumpet		Plays green musical notes when used.	0.50	None.
Piggy Bank		Gives platinum or gold coin when used.	7.50	Enlightened of the Cult, Pirate Corsair, Black Knight, Warlock, Priestess, Hero, Infernalist, Grynch Clan Goblin.
Present (Explosive)		Explodes when used.	6.00	Undead Jester.
Red Balloon		Can be hung on walls.	0.10	None.
Spellwand		Turns you or someone else into a monster and sometimes spawns a Mad Sheep.	2.00	Undead Jester
Surprise Bag (Blue)		None.	10.00	None.
Surprise Bag (Red)		None.	10.00	Fluffy, Primitive, Tibia Bug, Bones, Hacker, Undead Minion and Minishabaal.
Suspicious Surprise Bag			8.00	Undead Jester.
Valentine's Cake		edible	5.00	Grynch Clan Goblin
Yellow Pillow (Supersoft)		None.	16.00	Undead Jester

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