[As someone who has grinded before, Ren does have to admit it can be a little crude sometimes.]

Well maybe sex is a little too much...[honestly he just used that word because at least Yusuke would understand that one. How can such a poetic man with a varied vocabulary that would make most people blush be so... simple about that sort of thing?]...it's usually when two people rub against each other to stimulate and entice the other.

[He thinks about doing it with Yusuke but...maybe that's crossing a line. He did call it crude, after all. Still, he does walk closer and pretends to do it by rubbing his elbow against his friend's.]

Like that, but meant to make the other person want to go farther.