No, but if you were small enough and could breathe underwater, it would probably be no different from a giant waterslide... only there'd be less pee in the water! xD
Being flushed down the toilet is impossible in fact. If it were though, you'd drown quickly, smell awful, possibly swallow feces and urine, and just be a mess. Not worth it. 2/10 would not do.
There are some water park structures based on toilet flushing. Try it
I have a waterpark close to home that has one of those "toilet bowl rides" and it seems to be scaled down quite a lot. It still is somewhat fun, but there's no pulling you downwards harshly or anything like that.
But... if there was a big enough toilet and it wasn't filled with urine it might actually be fun to be flushed down it as long as I didn't drown.
