No!

     One time I was eating dinner with a few people I had just met in the dorm.  Everything was going as well as it possibly could - the food was good, the hall was not too noisy, and the people were exciting.  The boy next to me introduced himself and ask where I was from.  Unfortunately, I had just taken a big bite of roasted eggplant and was thus occupied with chewing.  Not to be deterred, he started guessing where I was from by state while I chewed the aubergine.  I shook my head for each wrong answer while also signing "no."  Finally, I gulped down the remnants of the eggplant and said, "No, I am from New Mexico."
     “Oh, that’s nice.  Am I talking too much?”
     “No, why?”
     “You’re making that sign …” and he showed the yapping gesture that looks similar to ASL ‘no.
     He had mistaken my signed "no" with the "talking too much" gesture.  An easy mistake, my "no" had gotten a little bit sloppy, but I explained to him that while I cannot talk while eating, I can still sign!  I then showed him the sign for “no.”  He said “Cool!” - he happened to know the ASL alphabet and we continued the rest of dinner talking about sign language.
     An interesting start to a good friendship!

How to sign "no"
     http://www.lifeprint.com/asl101/pages-signs/n/no.htm