Some one who is worth getting in bed with. Fuckable. Male or female. If a male is Shag-a-rific, they most likely have a large 'love loaf'. Once you have them in bed, they are guaranteed to be absolutely amazing and have a great 'shag'.
Girl- Do you see that guy over there? He is definitely Shag-a-rific!
Friend- DAMN! I agree, I bet he also has an amazing Love Loaf. *wink.wink.*