Before you go and muck up a perfectly good filter or lens, try a piece of food wrap, (Glad wrap, Saran wrap or whatever it is called in your locale). You can fix it with a rubber band.
Once in position you can 'modify' your Saran filter in many ways in order to deliberately degrade the image ala Lomo style. Once you have finished you can remove it in a second without any cleanup of your lend or good filter.