Usopp bringing Nami in his shit
That's funny, case Ulti doing like same to Pay Pay LOL
But then again it's like battle of Brain vs Brainless, what is more important that Usopp created Nami's weapon, so this fight will be fair in all terms, case those two will come up with great plan and will defeat brother and sister pair.
Also this is great for develop of Nami and Usopp relationship, they really similar to each other, and maybe could called as brother and sister in some terms)