Is it wrong to let my sister spend my birthday gift card?

My (17m) parents just gave me a $25 Starbucks gift card for my birthday. My little sister (14f) is obsessed with coffee drinks but it’s not her birthday obviously. I asked if she would spend it up and not tell our parents and she agreed. The only thing is her birthday is next month so she will likely get a gift card as well and then she will have spent both mine and hers without our parents having a clue. Is it wrong to let her spend mine without our parent’s ever knowing?