I don't #
It's the sound of two people who don't know anything. It's like saying, 'Me neither' but even worse. It's like the end of a bad movie.
"He said, 'I don't #.' I said, 'Me neither.'""
"She said, 'I don't #.' I said, 'Me neither.'""
"He asked me, 'Do you get it?' I said, 'I don't #.'"