[0.97] Jubilation

They will mean these no doubt.

 Spoiler

Small B-Day Surprise
Get a random Cash Shop item when you open this box. Test your luck! After purchasing this item, open the box by double-clicking it in the Cash Inventory. Please keep in mind that you'll only be able to open the box in the Cash Inventory.



Medium B-Day Surprise
Get a random Cash Shop item when you open this box. Test your luck! After purchasing this item, open the box by double-clicking it in the Cash Inventory. Please keep in mind that you'll only be able to open the box in the Cash Inventory.



Large B-Day Surprise
Get a random Cash Shop item when you open this box. Test your luck! After purchasing this item, open the box by double-clicking it in the Cash Inventory. Please keep in mind that you'll only be able to open the box in the Cash Inventory.

There's an actual gach box event too

Gachapon Box - 04.27.11 - 05.10.11
Gachapon Box win lists have been updated just for 6th anniversary! Collect Silver Boxes and Gold Boxes dropped by monsters and open them with keys from the Cash Shop in order to get a prize! One Premium Silver Master Key can open one Silver Box, and one Premium Gold Master Key can open one Gold Box. To find the keys in the Cash Shop, go to the Event section of the Event tab, or go to the Game section of the Etc. tab. Gold Boxes now contain Timeless Items, shoulder items, enhancement and potential Scrolls, advanced scrolls. Silver Boxes now contain Reverse Items, shoulder items, enhancement and potential scrolls.