Here are two I've found:

This one is pretty short: untitled french mistake (http://floatxxaway.livejournal.com/6918.html) by floatxxaway and was originally posted in deancaskink.
"Misha can tell this isn't his boyfriend. But does it stop him from fucking him? Of course not."

And I haven't read this one yet, and the Misha/Dean is more implied, according to the pairings list: The Other French Mistake (http://lizzstomania.livejournal.com/6519.html) by lizzstomania.
While Sam and Dean were in an alpaca-ridden alternate universe, what happened to the 'real' Jared and Jensen? And then Dean and Cas get it on after Dean comes back.