Your birthday date (or at least the one you signed up with) is required in order to gift NX items to other users. This is needed to verify that the person gifting is the true owner of that account, providing a safeguard for hijacked users.
Once an item is gifted, the recipient will be notified immediately. The gift can be found by checking one's Inbox, and can be activated at any time the owner chooses with no expiration date.
Items can only be gifted with either NX Prepaid, or GP (at the rank of Staff Sergeant I). When gifting GP items there is a 10% commision fee that is automatically added to the cost of the item being gifted. Also for gp items, both the sender/recipient of a gift have to meet the rank requirements of the item being gifted. Therefore, the G36E could only been gifted to someone else if both you and the intended recipient are at least the rank of Sergeant. The maximum duration for gp gifting is 30 days for any weapon. 90 day or permanent weapons along with Clan items can not be gifted.