 You can make that kind of cash back just for buying the gas you have to buy anyway. Yes, I'm looking at the Upside app now, and there's a gas station at the next exit offering 25 cents per gallon cash back. Okay, I'm stopping to download Upside and fill up my tank. Download the free Upside app now to earn cash back every time you buy gas. Use promo code BLING to get an extra 25 cents per gallon on your first tank. You can cash out anytime right to your bank, to PayPal.