Have you ever watch this action(use the index finger to touch the tongue then continue to touch the tip of the nose)in Korean drama and wonder what it means??

I've got the answer!

Answer: When you sit down for a long time and suddenly get up, your legs gonna feel pretty numb. I dont know if this is believed only in korea but by touching your tongue with your finger then your nose, your body will revert nerve cells to the tip of your nose, thus not feeling that numbness in your leg. This is just an old belief by the way, not scientifically proven.

Thanks to http://www.asiafinest.com/forum/index.php?showtopic=19768 for providing this information.