Roccie said: Thats what i want to know. I've seen a million 4chan threads on it... and have yet to see an origin.
Pretty much, someone on a TTGL crack community posted a picture of some gashapon interacting with other toys, among those Rossiu laying on a dolphin plushie. The thing began with some jokes about Rossiu's real intentions towards the dolphin in the comments, then quickly spread as a meme when a couple of fanart about it appeared online. The rest is history.
It is funny that in my country there's an old legend about a pink porpoise (kinda like a dolphin) that disguises itself as a handsome man and takes women to bed... it must have been some excuse for girls to give their parents when they became pregnant, but it's amusing to see this picture and have this in mind