I have zero training with aggressive dogs but like most of us on here have walked through possible scenarios based on what I have seen and heard.

OBG above laid out the scenario the way I have played it out in my mind; give an arm and then start ripping eyes or genitals. At the very least attack the belly.

As a cyclist I have been chased by several loud, barking dogs. I suppose you could call them aggressive but I don't stick around long enough to see if they just want a lick.