J Lo was riding shotgun as Ben pulled up to the drive-thru Saturday at a Mickey D's in Beverly Hills ... and she was seen chowing down on one of those famous burgers, fries and washing it down with a fountain drink.
Ben grubbed down too ... possibly with a Big Mac, we can't really make out his sandwich in the photos.
TMZ broke the story ... Ben and Jen spent a couple hours at their new mansion over the weekend, so it appears they went from their $50 million+ home to the home of the $1 menu ... or vice versa.
You get it, right? Gotta save up when making big purchases!