18th Birthday Party design. 18th Birthday King - This awesome kings theme party crown design is perfect for a 18-year-old bday celebrant. Great for a boy who celebrates his 18th or eighteenth birthday and loves a royal-themed party. This king graphic birthday party design is great for a birthday boy who likes a king. Perfect outfit for a royal-themed birthday party or for costume parties and family photoshoots. Lightweight, Classic fit, Double-needle sleeve and bottom hem