This community, my friends, is a GODSEND. :D
The obligatory background: I'm writing/drawing a psuedo-rpf comic, wherein the protagonists are a humanoid and a Martian. At one point they have sex on the couch in the New York apartment where the story is set.
My query is, as at least one of the aliens could be considered superhuman, would the force or the motion of the sex be enough to move the couch? Or does it depend on the position?
If you don't understand what I mean by this, I refer you to "My Super Ex-Girlfriend" (this is not rpf for that movie, but the movie is where I got a few of the concepts from), a movie in which similar circumstances happen when a super-strength superhero tops a human in sex and manages to break the double bed and nearly send it through the bedroom wall. Because a couch is smaller and lighter than a double bed and thus by all rights wouldn't require as much force to do so, would alien-humanoid sex on the couch be enough to do a similar thing to the couch? Or would it not work, because in this case the stronger of the two is the one on the bottom?
I've searched for "couch", "My Super Ex-Girlfriend" and "friction of couch" on Wikipedia, and "friction of couch" on Google. It didn't really help matters.
Thank you in advance, and I hope my first post stuck to the rules. First post siesta time. :D
ETA: Thank you all for your advice. This has been a big help to me! :D