Track down Pretty Boy Lloyd, recover the stolen money, and make an... example of him

 is a quest in Fallout 2, given by Louis Salvatore. He wants you to track down a man who owes him money, retrieve the money, and kill him.

Pretty Boy Lloyd is hiding out in the basement of the Desperado. He'll try to talk his way out of trouble, but if he escapes you're in trouble with Salvatore. There are several ways to successfuly complete this quest. After finding Lloyd, you find that he doesn't have the money on him. You can kill him on the spot and pay Salvatore out of your own funds (he gives you half back as payment so you're out by $500), you can tell him to take you to where the money is stashed, or you can hide and follow him when he tries to escape. Once you reach the correct grave at Golgotha, make sure that Lloyd does the digging to avoid the landmine he has buried there (adds plastic explosives to your inventory). If you head down the grave at this point, Lloyd will escape and you will have failed - make sure that Lloyd goes down first. If you wait too long before going down yourself, Lloyd has disappeared and escaped. A better way to handle the job is to either follow him down into the grave immediately and kill him (karma loss) or else drop the landmine down to kill him. The landmine is quick and easy, but plastic explosives are more expensive than bullets - your call. The $1000 are in the footlocker. Lloyd doesn't have much of value on him. To avoid karma loss, an alternative method may work: follow Lloyd down, exit combat and sneak up on Lloyd, then use steal on him and plant dynamite/plastic explosives on him (two of either may be required, or weaken him with gunshots before sneaking). Be sure to sneak away to safety. Lloyd should blow up without any loss of karma on your part. Salvatore will still reward you for this.

Disposing of him will net you 500 experience points.

Return to Mr. Salvatore and give him the money. He'll pay you $500 and you'll gain 500 exp for completing the quest. Assuming you were courteous, he gives you a second quest: Collect tribute from Renesco.

Behind the scenes
There is a reference to Sergio Leone's "The Good, the bad and the ugly movie", when the Chosen One say "You see, in this world there's two kinds of people, my friend: Those with loaded guns and those who dig"