Hip Hip, Hurray, the kids have lasted 100 days of school! To celebrate this exciting milestone, most elementary schools and kindergartens love to dress up in costume, as well as enjoying fun activities throughout the day. A classic 100th Day of School costume is a grandma costume or old man costume. Look no further – from grey grandma wigs in an array of hairstyles, to a crazy cat lady costumes, kids will find exactly what they’re looking for. Team a granny wig with fake glasses to complete their old lady or old man look.