The nickname comes from One Piece, the long-running anime and manga by Eiichiro Oda, where the cook Sanji affectionately calls his crewmate Nami by the honorific Nami-swan. That running joke has become shorthand among fans for Sanji's exaggerated, lovestruck devotion, and short voice clips of it circulate widely in fan edits, reaction videos and meme compilations. Because the phrase is instantly recognisable even without context, it continues to work as a quick, affectionate punchline for One Piece fans sharing moments centred on Nami.