curtains (noun) ++ offensive term for the female genitals using this term to describe an induvidual girls parts, when she is present will invite quite a lot of abuse, as it alludes to a female being well packed and not very clean, i.e. 'Mary, I bet when you're in the shower with the window open, your beef curtains flap around in the wind' followed by a slap and a thud as john hits the floor.
BEEF
Meaning of BEEF in English
Slang English vocab. Английский сленговый словарь. 2012