The ability to get a special set of "skills" that are just cosmetic emotes. Simple ways to communicate with other players without actually chatting.
Optional Implementation Details
Could be located in the skills panel, or in their own separate panel, such as a dock on the bottom of the chat box with icons you can hover for a tooltip and click for the animation to trigger.
Might be worth investigating whether they can be used while in combat, I would say no. This is because some of combat is directly influenced by seeing an animation so you can dodge it. So perhaps a shared global/emote cooldown would avoid that problem.
Investigate targeted emotes vs. just facing the direction your character already is.
Wave - Wave arm hello
Nod - Nod head yes
Shake - Shake head no
Flex - Flex biceps
Point - Point in the direction you are facing
Scratch - Scratch head with hand