Ring-a-Ding-Ding!

 is a quest in Fallout: New Vegas.

Quick Walkthrough
OR OR OR
 * Speak to Swank at the reception desk when first entering Tops Casino. He'll assist you in killing Benny if you pass a series of 3 speech checks, or 2 speech checks and you have in your inventory the distinctive cigarette butts, his lighter, and the note from Novac. He'll return all weapons to you if you convince him of Benny's treachery. Eventually, kill Benny, work with Benny, your choice.
 * You can speak to Benny directly.
 * He'll make you wait in a presidential suite and flee, his bodyguards will ambush you with 4 guards at the same time.
 * Passing a speech check of 60 will make him go alone with you to the suite, do as you see fit.
 * Confront Benny on the Main Floor, turn the whole Casino against you
 * Speak to Yes Man in the suite (13th floor behind the double doors) to find out Benny's plan and about the Platinum chip.
 * Once the player has gathered the necessary information, they can leave the Tops.
 * NCR and Caesar's Legion will be neutral toward the player after this quest regardless of any past crimes committed. Representatives from both factions will approach the player with pardons and opportunities to work for them.

Detailed Walkthrough
Now that you know Benny is at the Tops casino located in New Vegas, it's time to go find him. You can deal with Benny in a few ways:

I. If you speak with Swank, you can convince him that Benny needs to be taken care of (Speech 45). He'll give you Benny's Suite Key and return all weapons secured when you enter the casino. Find Yes Man in Benny's Suite and return to Swank. If you choose to take Benny out, Swank will send Benny to his room alone, where you can talk with him and also choose to kill him. This won't cause the casino to become hostile to you. There are other dialog options with Swank besides Benny needing to be taken care of, and other options like working with Benny when you talk with him. Note: Killing Benny in his suite, regardless of circumstances will not cause the casino main floor to become hostile to you (tested four times on XBox 360).

II. If you speak to Benny and choose the peaceful resolution options: No guards will come after Benny's been killed and casino will not turn against you; four guards will come if you forgive him and let him escape. Note: When he was set free he takes off and he hasn't been seen since, so not sure where he goes exactly.
 * He will give you the key to the Presidential Suite and promptly send four bodyguards to kill you, fleeing the Tops Casino to The Fort.
 * If you pass the speech check of 60 to get Benny accompany you up to the presidential suite he will make you an offer. You can accept, kill him, or forgive him and let him escape.
 * If you have the Black Widow perk, it is possible to have Benny wait for you at the suite, where you can either kill him then, sleep with him then kill him in his sleep, or sleep with him and then fall asleep. If you sleep with him and fall asleep he will be gone in the morning and will have left you a note.
 * Benny will then be captured by Caesar's Legion. You will see him at the Fort and Caesar will give you the choice to decide how he dies or you can decide to help him escape. You only have two choices for his death; the first is crucifixion, and the second is battle him in the arena in a fair fight. If you decide to help him escape you will either have to kill all the Legion in the Fort, or give him a stealthboy and a bobby pin to help him escape. You must have a high sneak skill and a stealthboy for yourself or the Legion will become hostile. You can ask him what he will do if you set him free and he tells you that it's your choice; he can either take over the strip at your side or he will walk off into the sunset and never see you again. However it doesn't give you a choice to pick one or the other after that dialogue; you can only kill him or set him free.

III. If you choose to confront Benny on the main floor of the casino, it will turn the whole casino against you.

Speak to Yes Man/Swank to conclude the quest.

Outcomes:

I. Benny was killed, Swank become the new boss and platinum chip recovered.

II. Benny escaped with the chip, and later got caught by the Legion.

You always get the Presidential Suite Key, either during the quest/found it on Benny's corpse.

After speaking with Yes Man, you will have another option for New Vegas, opening up the Wild Card series of quests.

Behind the scenes
The title of the quest is a reference to Frank Sinatra's 1961 song Ring-a-Ding-Ding.