Sexual perversion; man who enjoy's spreading his man seeds to others through baking his love juice into cakes and other tasty treats.
A Fratpacker goes into work with a lovely homemade cake, baked fresh that morning. Little do his fellow workmates know, the cake is spiced with several spoonfuls of his very own love juice.
Oh my! Did you see those flatcockers in action?
I live in the South and this word has been in use for many years here. I was surprised it is not currently featured at urbandictionary.com.