Sometimes a map will have a randomly placed event item in it which can be collected by the mouse to purchase items from one of the four mice in the event map. Once the mouse collects the item on the map, the corresponding event item will appear on your back and will turn ghostly where you collected it on the map, indicating that you have already collect the item. The item can't be obtained until the mouse bring the cheese back to the hole. You can spend these currencies on the event map in the shop listed below.
Five seconds have to pass before you can collect the event item on a map. If you are revived by a shaman using the Ambulanceskill after collecting an event item, you will still have the item when you respawn, negating the need to collect it again, despite the fact it no longer appears on your back.
Obtaining 30 of an event item rewards 25 tickets (25); the current number can be seen in the Adventure Calendar.