A male/female of a rather promiscuous demeanour who has higher than average amount of notches in his/her bedpost.
"Man, I think Karen wants a bit of you."
"Karen? No way man, she's had more sausage than a butchers dog!"
To describe somethins as 'xyz as a butchers' means 'very xyz'. Orig. from the TV advert for Butchers dog food, with the catchphrase 'Is your dog as fit as a butchers dog?'. Hence, to describe a girl as fit as a butchers , or fit as a butchers dog means she is very fit.
Paris Hilton is fit as a butchers. (meaning she is very fit)
It's hot as a butchers. (meaning it is very hot)
an ugly girl who will swallow/take any type of 'meat' from anything with a pulse.
its the end of night and you still havent pulled anything decent, so in desperation you revert to a 'butchers dog'