Unfriendly Persuasion

 is a quest in Fallout: New Vegas.

Quick walkthrough
Marcus asks you to convince some NCR mercenaries to go away peacefully. With 65 speech you can simply ask them to leave and complete the quest.

If you ask them how much it costs to bribe them they will say 2500caps. You can get the caps from Marcus by asking him. If you then use speech to convince them to leave for free you have just earned a mint. Finally you can just kill them all, this is actually pretty easy considering that they all never move and can easilly be taken out with a silenced scoped weapon from afar for a sneak attack critical. To make it even easier Marcus and a random mutant will come to your aid! In fact they even have enough health to kill them all for you. The downside of course is NCR infamy.