Tiki Jax.

I have absolutely no way of visualising my idea, but here's what I have in mind, a skin that turns Jax into a Hawaiian tribesman. Firstly, imagine him completely naked. Then add tattoos on his back. Now put a leaf skirt on him. Then add something like leaf or root armguards. Now give him a pineapple or leaf helmet or decorate his hair in some way. Then give him a Tiki mask to cover his mysterious face. At last, his weapon will be a pineapple on a stick. It could be a normal skin, but seeing how Archduke Nasus was released on April it might be a good contestant for an April Fools skin. For ability effects, I have no idea. Maybe some juice will come out of his pineapple when he hits something or a coconut will appear when he activates his ult.

PS: I don't even play Jax.