Grosgrain. You prepare a whole bunch of helium balloons the night before and put them in the child's room while they sleep. When I saw a do-it-yourself helium balloon set at The Warehouse a couple of months back I decided that this would be a fun way to celebrate turning five!
I inflated about 15 balloons - but I think that more is more when it comes to balloons and I think if it hadn't been so late I would have done all of them. It was too dark to show the balloons in her room, and she wakes up so early so we didn't catch her initial reaction.
The balloons are now everywhere. To avoid them escaping the Sweetheart tied them down in numerous locations. As I type, the helium has worn off all of them, and there are some rather forlorn looking balloons with silvery tails trailing along the floor.