It's on their home page, but I am linking to their Terms & Conditions page. 20% off everything in stock.
20% discount applies to Web Store purchases paid for at time of order by credit card only. Web orders must be received between 00:01am Friday 6th December 2013 and 23:59pm, Tuesday 10th December 2013 to receive discount [all times are Australian Eastern Standard Time (Sydney)]. Discount does not apply to email, fax, phone, on-hold items, orders posted to Koorong, BPAY, prepaid orders, in-store orders, orders charged to a Koorong account, bookstalls, nett priced items, tickets, licences, gift cards/vouchers, donations, eBooks, or backorders. Items cannot be set aside for customer pick up.
Thanks OP.
Looks like no one will comment due to resultant religious flame war :P
On a lighter note, have a great weekend all!