This plugin adds an item where you can do gestures with your (Right) Hand.
Simply equipping this item will make you Wave.
Clicking LMB (Left Mouse Button) will make you do a Thumbs-Up.
Clicking RMB (Right Mouse Button) will make you do a Facepalm.
You can craft the Gestures item for free in the General crafting tab of your player inventory under the category "Gestures".