Hat's Entertainment

 is an unmarked quest in Fallout: New Vegas.

Quick walkthrough
When previously having obtained the Atomic Wrangler room key due to successfully completing the quest Debt Collector, you can have a go at getting another copy of it.

Locate Caleb McCaffery and take posession of his hat. This can be achieved by either killing him or with a high enough speech skill, he can be convinced to give it to you.

Return to the casino and as a reward for the hat you get another key, the Garret's gratitude and some good room company.

Detailed walkthrough
After the quest Debt Collector, Talk to Francine Garret she will tell you a man by the name of Caleb McCaffery has stolen caps and has fled to the strip. So she asks you to go and kill him and to retrive his hat as proof.

Go to the strip to find Caleb near the outside of Gomorrah and initiate coversation with him. You have 3 choices, One involving no dialogue.

You can take the PEACEFUL Approach and tell him you will offer him to hand over his hat so he can go free, and with a high enough speech check, he will do this. Now all you have to do is turn in the hat to Francine to complete the quest and gain his room key as a reward.

If you wish to take the less peaceful alternative then select the second option telling him that you are a collector for the Garrets and ask him to hand over the caps. He will then say he "Rather not waste the ammo but if you insist, draw" and combat will be initiated, He carries partially weak weaponery and low class armor so killing him should be easy for a high leveled player. Take his hat (and/or any other items you might find valuable) off him and return to Francine to claim your reward.

Alternatly you can sneak attack him without initiating dialogue and avoiding battle altogether (if you are able to instant kill him from behind) and taking his hat and proceed accordingly.

Taking the peaceful solution Caleb will remain there bald. If he is there for the remainder of the game is unknown.

Rewards
Atomic Wrangler corner room key, free rent, ability to have sexual relations with Fisto or the Beatrix Russell.