The Legend of the Star

 is a quest in Fallout: New Vegas.

Quick walkthrough
Collect 50 Sunset Sarsaparilla star bottle caps and deposit them in the machine in Sunset Sarsaparilla Headquarters.

Once you collect enough, another collector will come to assassinate you. You can kill him and take his 8 star caps.

Detailed walkthrough
In order to complete this quest you need to find 50 Sunset Sarsaprilla Blue-star Caps and return them to Festus. Festus is located inside the Sunset Sarsaprilla headquarters, which is south of The Thorn and east of Jacobstown. Upon completing or failing this quest it unlocks another quest.

Once you give Festus 50 Sunset Sarsaprilla Blue-Star Caps, he will tell you the story about the drink. After he is done it will say quest failed, don't worry because you will get another quest called A Valuable Lesson. You will then make your way to the marker on the map. When you get there, there is going to be alot of caps in Sunset Sarsaprilla crates. Go to the Dead body in the left corner of the room and pick up the Holotape. You will then get the achievement for completing The Legend Of The Star for 20 gamerscore. Along with the holotape there will also be a unique laser rifle called Pew Pew, Its DAM is "48" and Its DPS is "112".