Smooth-Talking Criminal

 is an unmarked quest in Fallout: New Vegas.

Quick walkthrough

 * Talk to Francine Garret.
 * Talk to Santiago.
 * Talk to Mick.
 * Talk to Santiago, again.

Detailed walkthrough
Talk to Francine Garret of the Atomic Wrangler Casino and ask her if there's some work to be done. This starts the larger quest Debt Collector.

One of the characters who has to pay up is Santiago, a smooth talker residing in a Squatters camp near Freeside's East Gate. He is trying to talk his way out it by telling he's a VIP at the Casino and offering you a password to get a discount at Mick & Ralph's.

Believe and subsequently pay him (with Barter skill less) or use force to get the money that way.