You can now order M&M's customized with a photo. The photo, presumably a face, is printed in black food-grade ink on a centimeter of space. From the "Do's & Dont's":
Please don't use objectionable words and phrases. No obscenities or inappropriate images. We don't want to leave a bad taste in anyone's mouth.
Custom Printed MY M&M'S® are for personal use only. That means no images or names that belong to a business, product, celebrity, specific sports teams, major events, landmarks, or schools or institutions.
To avoid any confusion and keep everyone safe, we will not print any reference to drugs or prescription items, especially those that are in pill or capsule form.