Looking for a cool idea for a 21st birthday? Here you can find 31 birthday party ideas for perfect 21st birthday ideas. Shots in Syringes, Cup with Names, 21st Birthday Cupcakes, Games, Decorative Bottles, Cotton Candy and Rosé, Chocolate Fountain, Punch, Plan a Photoshoot, Boozy Cake, Balloon Bouquets, Memory Bottle, Decorations With Flowers and Glowing Figures.