I started to notice the term in relation fo fandom-meta and yaoi but didn't really take too much notice until I started to notice authors talking about 'bukkake' in relation to yaoi-pr0n and yaoi manga. Hmm, and this has ben happening for about 2 or 3 mothns. So, to answer your question a surprisingly large number of yaoi-fics are using it as part of their synopsis.

Great Amusement.

To educate the mass. My work is done.

MWAHAHAHAHA!

I'm pure as snow and a Genius too!

Caffeine makes EVERYTHING possible!

I've noticed them in the GW fandom, the FF fandom, the FMA fandom, and I'm pretty sure sooner or later it is going to spring up in the Naruto fandom. The thing is it is often used by people in fandom who can either a)Speak Japaense, b)is heavily into the meta of the J-media/W-media, or c)I have no idea how they came to know the term ^^;;;

If you think about it the whole makes perfect sense, especially in relation to yaoi/BL manga... and quite a few of the fics... *koffs*

It is 'Fandom-Osmosis'! I speak the TRUTH! Um, are we speaking of 'osmosis' or 'bukkake'? The former I say you were an intelligent child, the latter I say you were a perverted child. Personally I think the latter has appeal :p

OMDF! MWAHAHAHAHA! That is good! Yes, manga, so much manga. I love manga. (But PoT is strange and full of crack, so, it is almost, well, accepted.)