It looks to me like Clark caught Lois restocking her Double Fudge Crunch Bars, late one night. See, he's pulling down his glasses to take a super-quick peek. Lois' stance looks more defiant, like she's unwilling to admit that it's those sweet chocolate-y confections that helps her make it through the rough times.
It's her typical save-face and denial pose, with Clark's okay, but I know better pose behind her.
