When you have just taken a huge bite of food and then you find out you have to go talk to someone.
At which point, you stand there chewing with your finger up as if to indicate one more minute.
After chewing has commenced, you continue on your way.
Person A: *Bite*
Person B: "Dude, James needs to see you"
Person A: "Ok, hold on, let me chew" ........................*Chew Stalling*
Person A: "Oh hey James"