Yuudachi from Kantai Collection's catchphrase-poi.
To be used only when there is particular emphasis on the phrase "poi" (when used standalone, "poi" is in romaji, a pun, etc...) and the use is related in some way to Yuudachi, not just as a comparative particle of sorts-poi.
Not to be confused with the festival goldfish scoop, the tethered weights (sometimes lit) used in the eponymous performance art, the polynesian staple food, a certain cat-eared maid from a certain mobile game or even the 3d adventure platformer game-poi. It's also not to be confused with the onomatopeia for throwing a light object-poi.