Why did the banana go to the gym?

This joke is a classic example of wordplay, hinging on the double meaning of "fit" and a clever sound-alike for "peel." When we talk about going to the gym, "fit" means getting into good physical shape, usually for health or appearance. But for a banana, "fit for the peel" takes on a whole new, literal meaning – it needs to be the right size and shape to stay snugly inside its own skin! The humor here plays on the expectation of one meaning and delivers another, equally valid, but comically absurd one.

The humor also comes from the delightful absurdity of picturing a banana, a fruit (Review) known more for potassium than pectorals, hitting the weights at a gym. Bananas themselves are a common fruit, often associated with healthy eating, making the idea of one actively pursuing physical fitness even more playfully ironic. It's a simple, sweet pun that gets a chuckle by twisting our expectations of what "getting fit" truly means and applying it to a very un-gym-like object.