The human centipede movie, isn't it? The director is said to have claimed that the medical knowledge described in the movie to attach three (or more) humans by connecting the mouths and anuses is perfectly verified, only to have the entire movie laughed at by professional doctors. Thus it should be possible to reproduce the said fleshy contraption in Gensokyo, especially by hands such as Eirin.
I just saw that movie...one of the most disturbing things i've ever watched. It does offer a very different perspective on life if you're interested in that sort of thing. Never thought I'd be seeing a parody of it.
As concerned as I am with the current overuse of the pooling feature on this site, this image does suggest to me the possibility of one for "The Most Likely Crossovers".