Because, In the German translate [version/anime/manga] they changed his name to Ruffy. It's easier to speak it out for they so. I guess some people prefer "Ruffy" than "Luffy" because it's maybe sounds better for they.
gorgeous! good job!!! Finally some cosplayers with great bodies to match the charactesr (oh shi- i just pissed off a lot of cosplayers). Love the pose, excellent outfits, and... ADORE... your choice of pairing.