The corn-shaped vibrator made me laugh so hard when I saw it!
I like the suggestion of grapes, but for some reason a kiwi or a lemon is coming to mind. A little fuzzy bullet shaped like a kiwi might have an interesting texture, and either it or a lemon would be small enough to be easily insertable.
Xavier7: Plantains sort of look like bananas, but they need to be cooked since they're hard and inedible when raw. Many people peel, slice, and fry them in oil; the result being crunchy slices that taste vaguely like potato chips.