A zebra doesn't eat apples
A zebra doesn't eat apples means you're being a total idiot and need to stop making stupid excuses.
Why did you fail the test? I don't know, I just didn't study! A zebra doesn't eat apples!
You missed the bus? A zebra doesn't eat apples!
You said you'd clean your room, and now it's a disaster. A zebra doesn't eat apples!