From this weeks MSE email
How: Buy via group buying site, Groupon*, from 12.01am Weds 15 until midnight Thurs 16 Dec.
There are two vouchers available, they must be spent in one transaction.
To use online: Buy the deal on the Groupon national page. The online code will be sent to your registered email address.
To use in a local store: Buy the deal from the Groupon local page. The printable voucher will then be emailed to you.
Restrictions: It’s not valid on sale items, and can’t be used with the 15% off code available in the American Apparel newletter.
It's non transferable. Not valid on multi packs, California Select Vintage, Multibrand products, shoes or at Outlet locations. Not valid with other offers.