Crazy Naked old men selling A little known flavor of Nuka-Cola "Yellow Nuka cola." It has an "interesting" bouquet. You come across them in vegas selling this rare Nuka cola that you can only get from them.
Spoiler Well, it's pretty much implied that they pissed in Nuka Cola bottles.
You feel very dirty and wrong after drinking it, if you drink 10 of them you figure out it's secret! You can then make your own

If you have intelligence of 9 or higher you figure it out after 2.
Gain a
perk after selling 12 bottles of your own making, to others. It is called
"Dirty Trickster" your barter skills increase 25% and you become alot better at deceiving and lying.
negative side: your karma drops a couple points everytime you sell it to someone and you become known as the
"Dirty Man/ Woman" in New Vegas. Parents don't want their kids to be around you. Anyone that has kids or knows the secret behind Yellow Nuka cola will not buy or trade with you, unless they to have bad karma.
can't sell your own "yellow nuka cola" to the crazy old men.
Idea 7.