You mean fics they discover about themselves-- oh gosh, anything. The funniest thing would be a really terrible made-up fic with lots of implausible over-the-top sexin'. Or one where (wasn't there a paparazzi stalkerish prompt?) where someone has gone through tumblr-style and done a list of reasons why Hawkeye and Black Widow are totally secretly together and in love and just need to confess it to the world and get married b/c you know, EVERYONE ON PLANET EARTH SHIPS THEM TOGETHER.

Or something. Kind of like certain actor-y people we know... **whistles**

O.M.G. You could do the funniest fic ever just in tumblr tags about H/BW (as if they were actual people).