Parents (and let's face it, probably some grown-up fans too) have been rushing to buy Asda's Thomas the Tank Engine Advent calendar.
The calendar first went on sale two days ago and sold out quicker than Santa's sleigh can fly.
So what's so special about it we hear you ask?
Its popularity is mainly due to what's behind each cardboard door, because it isn't just filled with measly chunks of chocolate.
Instead it is packed with mini toy cars, trains and planes.
It features 24 Thomas MINIS including six exclusive exclusive MINIS with holiday-themed decorations.
Asda has now restocked the calendar online so if you know a Thomas fan - however big or small they are - it's wise to snap one up now before they sell out again.
The supermarket has confirmed they will restock the item if it sells out again but it has not said how many of them are availblae.
It costs £30 with £2.95 for delivery or click and collect for free. You can buy the calendar here.