I'm pretty sure this is a reference to the chapter where Bon Kurei posed as a very sweaty Nami as a means to distract Hannyabal. Do any of you even read One Piece? The trap tag is appropriate here, as well as "sweat," which I will add myself.
And you can clearly see the character in Bon Clay's characteristic pose, sporting an appendage that Nami normally doesn't have. How much more do you expect an artist to do when drawing a shapeshifter?
It's not like it's just a random pic of Nami. There's clear visual indicators of who the pic is actually of for people who actually know the series.