Level 4 is the underwater level. Level 5 is snow. I didn't create the snowman and igloo seen here, but I did arrange the version of "Let It Snow Let It Snow Let It Snow" in the background. I stole the snowflake shape from Wingdings.
I also made a black outline for the hamburger because apparently people requested it. So I obliged, although I don't personally like it, but OK. So now I need to design 5 more levels and some ending screens. One for a non-perfect score (<1000) and one for a perfect score (1000) even though I doubt anyone will actually see the perfect score ending. You'd have to shoot all 80 milkshakes in all 10 levels without getting a game over. (By the way, the lowest score you can get and still get to the end is 200.)