So I took a stab at redesigning the hamburger as well. This is what I came up with:

I should note that looking at this picture, I should probably change the lunar surface so the score is easier to see. And this is my palette now:

The second color in the palette is reserved for the score, and I can change it on the fly to whatever I need to to get the score visible. I had to put in every color for the rest of the sprites (which are not visible in the game) because the program I use to convert sprite data into Game Gear data apparently does not recognize unused colors in a palette. But since 4-bit images have 16 colors and the sprite palette for Game Gear et al. has 16 colors, it works okay.

There are only 14 colors in that palette though. I guess I didn't really need 16 of them. The french fry is still yellow and the milkshakes are still the same (strawberry, vanilla, and chocolate.) I even worked on the onion rings and chicken nugget, although I haven't seen them in action yet in the game so far.

And I must admit the burger looks better with toppings, but apparently, as people in a certain thread have voted, pizza tastes even better.