That's one of my favorite lines too. The interaction between these two is just wonderful.
Doug Jones did an interview some time ago and he told this wonderful little story that happened during filming one day. A basic fact of life with rubber suit actors like Doug is that it's very hard to see out of those masks. (look through a couple toilet paper cores and you've got an idea of what it's like.) So the scene is they have to walk down a hall and turn left at the end. Before 'action' was called, Doug briefly put his hand on Ron's shoulder so he knew where Ron was. 'Action' is called and they start walking, as they're going along, Doug gets a bit confused about the length of the hallway and reaches out to touch Ron's back so he knows when to turn. 'Cut' is called and Doug breathes a sigh of relief and then Guillermo yells at him.
"All right, let's do it again. And Doug, do you think you can do the scene without grabbing Ron's a$$."
Poor Doug thought he was being so discreet, but he watched the dailies and sure enough there he is walking along with his hand on Ron's backside. What I wouldn't give to see the outtakes for this movie.
>^^<