Jezebel recently ran this picture, an image from the back of this year's Sports Illustrated Swimsuit Edition, with the headline "The Back Cover of the Sports Illustrated Swimsuit Issue Tells You to Fuck a Piece of Chocolate."
The M&M custom ads for SI's annual spankbank bait is actually a tradition that goes back a few years.
Here's one from 2011:
|Via Social Media Trend|
|Via Sociological Images|
In fact, the "sexy green M&M" has been part of Mars Inc.'s strategy for several years:
It's intended as a parody. This year's candy pinup is a send-up on the Antarctic cover shot for which Kate Upton almost literally froze her ass off.
At this point, though, I'm not sure the humour is even there anymore. It's the other side of the food-as-sex trope that crosses the streams of primal urges in increasingly weird ways.