I love the idea of dressing your toddler up as a piece of fruit, it further enforces good nutrition while they're having fun. Well that's my story anyway!
I think this banana costume is gorgeous and would really suit a boy or a girl beautifully. You will need a shirt and pants to wear underneath this costume as it consists of just the 'inside' of the banana part and the banana skin part that you see here - not the black top and pants that the model is wearing.
You can also get this costume in an adult's costume if you want to wear matching fruit costumes this year.
There are other fruit costumes that you can wear besides the banana one, but I think this is definitely the pick of the bunch if you'll excuse the pun.
Another fruit costume that can look good is a Strawberry costume, but this one is definitely for the girls and not a unisex option at all.
I'm surprised there's not more fruit inspired costumes available to buy, but if you're looking at making your own I would look at fruits such as pineapple, a slice of watermelon, a kiwi or even an apple.