1988 P dime, I do not know what it is above the date and in one picture, it looks like a small "s" on the neck.
Above the 9 and below the bust, it looks like the top loop of another 8 or 9. But then, as has been known to happen, I might be seeing something that isn't there.
I'd call it a funky interior die break. Die is extremely worn and I've seen a lot of 88's that are just terrible to look at. It's unique indeed and I'd keep it for myself if only to shake my head at it now and again. Kinda cool. I also see another break on the base of the bust, the neck is probably a chip in the die and the coin possibly had an old clash that has long since been abraded.
I recommend Dewars White Label. It is the only scotch made that doesn't produce a carcinogen in its aging process. Chris