Right now, some AMEX cards are offering an extra supermarket bonus when you refer a friend. In addition to earning the standard referral bonus, you can also get an extra 5x on supermarket purchases. Most MR-earning cards seem to have this offer, with a spending cap of $25,000. For the cash-back Blue Cash Everyday/Preferred cards, the offer is an extra 5% cash back instead. However, each card can only receive this kind of bonus once through referring.
