An offie was a local off-licence liquor shop. It had been heard of twice in an episode of Series 3.
It was mentioned first by Vicky Pollard. She had been babysitting a couple's young boy, but threw a noisy party instead. When the couple returned to their vandalised home full of drunk teenagers and a calm Vicky Pollard about to "'ave it off with this bloke", they angrily asked where their son was, she unaffectedly replied that they sent him down to the offie to get more "fags", then stated that they gave him a fake I.D.