Liberty gives Humdinger a lapdance...

...similar to how she scrapes her feet after shitting. Since dogs scrape their hind feet after shitting, could it be that the dirt stains she was spreading in this scene were actually her own shit!? Remember she was clean in the scenes prior and it's only in this once that she leaves brown marks on the floor. If this theory is correct, then it's rated G for Ghastly Defecation! Liberty you nasty ass stray!