Rhyming slang: Wurzel Gummage, Dirty Rummage.
To approach of a woman you've just met from the rear, part her arse cheeks and donate a rim-job. This differs from the "Direct approach" where the woman lies back with her feet over her shoulders presenting her arse hole to the Rimmer, thus negating the need to rummage around looking for it.
Check her out! would you wurzel it?