Not too shabby sir. I like it. What a funny surprise that would be when you pull the rope out.

I’m a jumbo-climax kinda guy.

This will require a little surgery on your jacket: Create a buttonhole or, even put a grommet, in the jacket, hidden by the lapel and placed somewhat higher than where your thread-spool gimmick is located. Drape most of the rope back over your shoulder (under the jacket) so that it won’t make a sharp turn at the buttonhole or grommet, and pull about two inches through the hole, where it will rest hidden under the lapel to grab.

I just tested running the rope up the lapel on one side, under the collar behind the neck, and about halfway down the lapel on the other side. This plucks off quite well with a downward pull, although the amount of rope that can be concealed this way was a little shorter than what I wanted for the follow-on effect that I’d like to use the rope for. ( I do a ring-and-rope penetration routine using a five-inch ring and little over three feet of de-cored rope.) That suggested the grommet method to produce a rope that’s funnier for being longer, and also of a more practical length for the typical effect that uses a medium-length rope.

See also Gene Anderson’s loose-buttons effect from his Part-Time Pro lecture notes for another effect that might be combined with your loose-thread gimmick.