does anyone ever talk about "football wank" or "political wank" or "real ale wank," or is it just sf fans who get that?
I suppose it's all part of the standard bigoted view of fans as spotty unhygienic teenage boys who spend too much time reading books and not enough time getting drunk in gangs and bashing members of the minority of their choice.

Non-fannish stuff gets it too (http://www.journalfen.net/userinfo.bml?user=otf_wank). And fannish stuff does include (though more rarely than otherwise) non f/sf stuff, like the Celebrities (Non RPF-related) (http://www.journalfen.net/tools/memories.bml?user=fandom_wank&keyword=Celebrities+%28Non+RPF-related%29&filter=all), Pop Fandom (http://www.journalfen.net/tools/memories.bml?user=fandom_wank&keyword=Pop+Fandom&filter=all), and wrestling (http://www.journalfen.net/tools/memories.bml?user=fandom_wank&keyword=Wrestling&filter=all) categories. If that's any consolation....

I think it started as a handy metaphor and expanded to include other things, so that now the newer usage has only a passing connection to masturbation--there when someone wants to make a joke about chafing etc., but hardly present otherwise. For a more wtf-worthy (in my opinion) example of usage shift, look at #3 for "shit" (http://www.urbandictionary.com/define.php?term=shit) (waaaay down there). (And I also agree with mamadeb up there--when you adapt a foreign piece of slang, you don't necessarily pcik up all the associations that come with it. I think it tends more to come as just the basic definition and maybe a vague idea of whether it's rude, formal, etc., and if it enters into general usage it'll pick up a new set of associations for the new group that's using it. I always thought "wank" was a fairly light word--dismissive, but not, "omething squalid, something dirty, something to which no decent human being would ever stoop," and fairly low on the... vulgarity hierarchy. But it looks like that's not entirely the case.)