I've used that emoticon before. To me it meant that I was wanting to say something ugly. But I would never do that! So my mouth was sealed with a metal patch, bolted on...
I've (almost) learned that it's a bad idea for me to tease, because I ALWAYS manage to put my foot in it. It takes more smarts than I've got, as all my friends keep telling me.
I've used it a few times when I tease someone by saying something that is not necessarily real nice, but to let them know I was just teasing. Sort of, "Oops, did I really say that?"