It hadn't been Jo's intention to leave the geek to the Dog Bitch, but it wound up a convenient diversion anyway. Before the other woman has a chance to aim her gun at Jo, she's crouched down behind the monstrous wheel of her lifted Blazer, both hands in position on her pistol, ready to shoot if she has to.
She can tell from the mongrel bitch's laugh that she's recognized Jo. She'd been hoping to get back to the tunnels before the Dogs had a chance to find out that she's returned. She knows that running into one of the Hellhounds alone can be deadly for her-- they've always got backup just a bark away, if they're ever caught alone in the first place at all. She knows that the Dogs could easily see her as a loose end that needs tying. No one who could be an ally on her side even knows she's back, and if the Hellhounds came and killed her now, she doubts anyone would ever know. She's in a dangerous position, and her only hope is to pretend she isn't. Bluff, make the Dog Bitch believe she isn't totally alone in this world.
"I'm putting this fucking belt in my car, bitch," Jo shouts, unconcerned with the geeks her voice might attract. "You wanna stop me, you can fight me. If you're not too afraid to put the gun down and brawl."