I would not want to "sneak" food out of a buffet, among other things there is a "slippery slope" issue.
What I have done in similar situations, is asked whether I can pay something to take the item with us and explained my reason for wanting to take it (For example my mother was home sick one time, and my father wanted to bring her a piece of her favorite cake). In another case, I said how I felt bad that I had not finished something and hated to waste it The response has always been for the server to bring me a container to take the item on the house.
I know this isn't what you're asking, but we have actually taken a to go box from H&V before. My dd (I think she was 4 at the time) fell asleep before she has the chance to eat her food, and our server gave me a styrofoam box to fill up and take with us for her to eat when she woke up. I said that it was alright, but he insisted.
As for the piece of fruit, we have brought a banana with us before leaving CP
actually, some people can't eat more than a few bites at a time and graze all day. I am one of them. I tend to avoid the buffets because I am not paying $25-30 for 6 bites of food. Since I only make one trip thru the line, I wouldn't have ANY problem putting a few bites in a ziploc for later.
I do the same thing at non-buffets also. Today, we went out for lunch...i ate 3 bites of the appetizer, 2 of the desset and 3 bites of rice. We took my whole entree home. It just it what it is...
I know this isn't what you're asking, but we have actually taken a to go box from H&V before. My dd (I think she was 4 at the time) fell asleep before she has the chance to eat her food, and our server gave me a styrofoam box to fill up and take with us for her to eat when she woke up. I said that it was alright, but he insisted.
As for the piece of fruit, we have brought a banana with us before leaving CP
DS was just getting over an ear infection at the beginning of our last trip so he wasn't eating much and we had servers at a few buffets offer us boxes to take his food. They simply asked that we just box up what was on his plate and not go back to the buffet but that was fine with us. So I would think that taking a piece of fruit for later for a child would be perfectly acceptable.
I have a friend who once mentioned to me she packs little ziplock bags in her backpack... and then at the breakfast buffets the kids take an extra rice crispy treat or fruit with them for a snack later. If on your plate, then they're just going to toss it anyway. My kids take too many treats at buffets and can't eat them all, so may take the extras with us from now on to save for later.
We did take a piece of Pooh's puffed french toast from CP breakfast once when we were meeting my sister-in-law after breakfast as she really wanted a piece!
I wonder what would happen to the people if they were caught putting food in a ziploc? Could anything be done? Knowing how some people are at WDW, they probably think its their right to take food with them, lol.
We've been told by servers on many occasions to take a doughnut or fruit with us. One place told us that they put the fruit baskets on the way out to encourage people to take an apple or banana with them.
We usually end up with too many 'sweets' on our plate. I just wrap them up (if that's possible..can't do it with bread pudding!!!), and put it in my bag. If I wanted a piece of fruit, I would get it before leaving...bring it to my table and then tuck it away.
I seriously doubt Disney has any issue with it's guests taking an addlt pice of fruit, muffin or cookie as they leave the restaurant. I doubt that I have eaten enough to justifiy the ridiculous price I paid for that meal.