I have heard that it is if ONE, and only one, person finishes it. And I'd bet they mean FINISH it.
They do stand and keep a close eye, because my idiot friend thought he could eat the whole thing.The waitress said if it melts she'll give him a straw to drink the rest.not sure if she was serious , but she probably was.My friend couldn't finish it and got sick.By then it was a soggy,melty unappetizing mess anyway.
lol...but i'll probably get sick like your friend 