I once pulled a 3 ft string it out my cat’s throat because he was helplessly swallowing the whole thing. It was gross and uncomfortable at least, of not painful for him, but I think we Dodge a bullet that day. That was under supervision. The thing with strings is they feel the necessity to swallow them when they reach their throats. Yeah they go crazy with it.
You might already know this, but letting cats play with loose pieces of rope is kind of dangerous. My friend had a really expensive cat operation because the lil guy ate the entire rope and it screwed up his intestines.
My cat loves string, more than any other play thing. But I had to stop it when I found him with a, um… piece hanging out his butt. (And he actually chewed that one off at both ends, from a “fishing rod” toy.) Careful out there, friends of cats.