My understanding is that they can't. Trademark protections, IIRC, extend only as far as to not confuse people as to the source of some product. If you created a

My understanding is that they can't. Trademark protections, IIRC, extend only as far as to not confuse people as to the source of some product. If you created a parody to complain, and not to sell a competing product, then fair use would apply. Do you have any examples of when a Trademark holder has been able to prevent a parody?