Instructions:You can use the code 'EXTRAGAP' to get an additional 20% off sale items (it only works on discounted stock).
Here are the specific conditions attached to the code:
"Offer applies from 0:00 GMT 20 December 2014 to 23:59 GMT 21 December 2014 online at www.gap.co.uk and www.gap.eu only; subject to stock availability. Not available at Gap Outlet stores. To redeem offer enter code EXTRAGAP at checkout. Discount applied at checkout. Excludes gift cards and shipping charges. Cannot be combined with any other discount or multiple offer and applies to reduced priced/sale merchandise only. Gap reserves the right not to apply discount where it suspects fraudulent use. Not valid for cash or cash equivalent. No adjustments on previous purchases."