When we got Gracie the cat from the rehoming centre she had a kink and lump in her tail. Yesterday, she crept up behind the OH, who then stepped back and trod on it. There was a great yelp and a bit of growling, but ever since Gracie's tail has been lovely and straight and lump-free. I can only think Bernie trod on the end and it pulled her tail back into shape as she tried to yank herself free. Whatever, she's in no pain and her tail is now perfect!