Celebrate a special birthday with this vibrant “Sister of the Birthday Boy” birthday design, perfect for personalised T-shirts, hoodies, birthday shirts, party decorations, invitations, banners, and gifts. The colourful pink, blue, and gold design is ideal for sister birthday celebrations, kids’ birthday parties, family photos, matching sibling outfits, and personalised birthday merchandise. With a square format and transparent background, it is perfect for printing, sublimation, stickers, party signage, and digital birthday graphics.