If you need more time to think about it
"Hold on a minute there mister, something like this only comes around every many plus several lifetimes, I want to be sure that what you give me would be worth the trade, I mean, these chips exude flavor, I can smell them outside the bag and they actually give me an erection!"
"I shall throw in mystic concel for free then, you just sit back and I'll explain what some common human wishes normally result in. Riches is a normal request, massive wealth to set you up for a life time. That one is a fairly easy one for me, I can alter hundreds of data bases around the country to agree that you have millions, you will lavish in wealth, gather a army of free-loaders, have many brushes with the law that your money will buy away or at least lesson the sting. You will get crazy on drugs and booze, buying all kinds of toys. The potential drawbacks are being killed in a robbery by someone you know, being killed by your new wife who does it for your money, drugging yourself to death. Killing the wrong person after a long booze drug binge and actually going to prison for it, government seizure of your property and wealth, and simply having so much fun you spontaneously combust.