This is when you buy too much food, or order too much food and when you have it in front of you, you cannot eat it all and have to give it to someone else.
It does not mean that you have giant eyes. Or a tiny belly.
Gillian: Mary, are you going to eat all of that? You're taking a long time.
Mary: Yes. Give me a bit longer.
Gillian: Ok. if you don't want it, i'll have it.
Mary: No. I'll eat it all!
...10 Minutes Later...
Mary: Ok, I'm full!
Gillian: Does someone have EBTB's?