The term "fuzzy pickle" has its origins from the funniest rapper ever: Eminem. In one of his songs he speaks of Jennifer Lopez saying, "... I don't give a fuck if this chick was my own mother, I still fuck her with no rubber and cum inside her and have a son and a new brother at the same time, and just say that it ain't mine," which actually says a lot about how he feels about her.
Well, when I was at work one day I told a friend we should give a girl that fits that description a special name so that we could talk about them right in front of their face and they'd never know. My friend replied, "Fuzzy pickle!" And so, the fuzzy pickle was born.
So, quite technically speaking, a fuzzy pickle is a girl that is so freaking hot that you'd still fuck her even if she was your own mother. You would also cum inside of her, causing her to get pregnant. When the child was born you'd have a son and a brother at the same time, but you'd just lie and say that the child was not yours.