I wouldn't say it's particularly common but I can do it myself and know others that do it too. However the common theme for me is that the reason it happens is

I wouldn't say it's particularly common but I can do it myself and know others that do it too. However the common theme for me is that the reason it happens is species dysphoria (lack of tail, etc). It's easy to imagine having different parts from reality once I've been trying to imagine myself that way for years.