This is an implant perk, which means that you can't pick it when you level up. It is an implant named Probability Calculator. You can get it from Doctor Usanagi at the New Vegas Medical Clinic for 4000 caps. It is designed to aid the general Luck of the person it's installed in.
Adds +1 to your Luck.
Behind the Scenes
- In the perk icon, Vault Boy is holding an Ace-high Straight Flush, better known as a 'Royal Flush', the highest-ranking hand in Poker. The odds of getting a Royal Flush in a five-card stud are 0.000001539%, or 649,740-to-1 against.