If you want to make a gesture during a chat, simply click on the small button to the left of the "Send" button at the bottom of the screen. This gives you a choice of gestures you can use to help illustrate your points. When you hit "Send," the gesture occurs immediately on everyone's screen, if they own the gesture you used. VP has a basic a set of gestures (bomb, laugh, wink, smile, cry, phone, etc.)  most users will have these gestures, but additional gestures some users will not have and therefore will not see or hear them, they will just read the text associated with gesture.