Because there is alot of episodes where the Simpsons do something and Maggie is not there with them.
I used colours from one of those promo pictures of The Simpsons.
Now, I know there a alot of flaws with this. (perspective fail, The Simpsons in the back art too small and the program I used to make the outlines 'smooth' made the lines thick. etc.) now, I draw for fun and I haven't been in a art class since high school so yeah.
I drew this past 12 am and I noticed I didn't draw Homer and Marge straight, so I made them stand on a hill.