Hmm, bit annoyed as I wrote this draft a couple of weeks ago and now b3ta's picked up on the same thing and somewhat diluted its worth as an article. Never mind.
Recently, Waseda University in Japan finished scanning a rather old scroll. It's by an unknown artist from the Edo period and it's bawdy at best. As you can see from just one scene pictured above, it's basically the Bayeux of farting. Goodness knows what's going on or why it was painted, but you can view the entire thing at the link below:
Whilst it might seem like the kind of thing that would be a one-off, it turns out that there are several others. Famed uikyo-e artist Utagawa Kuniyoshi also managed one back in 1810
And although I can't find any pictures of them, it turns out that Christies auction house sold a collection of twelve fart battle prints back in 1992. They described them thus:
A collection of twelve small Japanese prints depicting 'He-gassen' (The Fart Battle) with officials in combat in interiors, possibly by Kyosai -- each 4in.x 5¼in., paper wrapper; a double sided album containing twenty-four prints by Watanabe Seitei (Shotei) and other artists variously depicting figures at leisure, birds, animals and flowers; another double sided album by Ikkei with thirty-six prints of scenes around Edo; three further albums; and a large print divided into three sections with a procession of figures travelling through a river landscape -- 23in.x 28½inYou can see the details of the sale at the link below. Apparently they only went for about a grand.
I have no idea why fart fights are big in ancient Japanese scroll painting, but it seems that they are indeed a thing. Here's a couple more images from the recently-scanned scroll: