what did E do?

Because e is a meme and school is only pain NO LAUGH

They left out E because they thought, "if you are dumb enough to get below a D, you might also be dumb enough to think E stands for 'Excellent', so we'll make it F for 'Failed' instead". True story

F for Fabulous I always say lol

i think they couldnt think of anything bad that starts with E

embarrassing, eccentric, elusive, etc.

E is a cool mark. You can laugh bout it