This puzzled me. Then I remembered that Dan went to the store for me and picked up some apples.
We are kinda picky about the apples we like. They have to be firm and tart when you bite into them. Our favorites are Honey Crisps and Granny Smiths.
Dan had picked up apples, not noticing that they were not our favorite kind.
We laughed later and talked about the apples not being so tasty. The kids noticed immediately.
When I went to the store I picked up some more Honey Crisp apples and put them in the bowl with the others.
So my best guess is that one of the kids, looking for the honey crisp apple, bit into each apple until he/her found the right one.
I haven't asked the kids yet to see who fesses up. I used the apples anyway, cutting out the bite spots. Hilarious!