Marge gets a tan. It's not until the last frame that you see that Marge has gotten a tan.  In the original comic, they're preparing to go on a vacation and Marge is getting a pre-tan so she doesn't get burned.  She tanned a little too much.

We all put on our masks, even if they just cover the crow's feet around our eyes. This joke's been done in lots of movies in some fashion or another.  But not in a comic ... it's a first!