Sabotage Becky's still
What? A still! Damn. Hey, here's the $100, and I'll pay you $500 to destroy it. You can use my crowbar, in the back room over there. That'll do a number on her stupid little still!”— Frankie
Go to Becky's bar, on the other side of town. Wait around 2 minutes for the guard near the door to move away and talk to the Craps dealer. Unlock the door by any means and go down the stairs, use a crowbar on the still. Sneak back out and return to Frankie for the reward. After destroying the still, Becky refuses conversation with the Chosen One.
Alternatively, Frankie can be persuaded (Speech check) to buy his inventory from Becky, which awards 900 XP and +70 Karma.
Frankie can be convinced to buy his liquor from Becky even after receiving the reward for destroying the still, this will net both experience rewards for a total of 1600 XP at the cost of 20 Karma.
In the unpatched game, Becky would accuse the Chosen One of destroying her still and refuse dialogue even if Frankie was convinced to buy his whiskey from her. [verified]