Within Teamwork Chat, you can use emojis in your messages to other users.
if you type : into the message field, you will see a list of emoji suggestions. This list will update as you type more characters, for example :s.
You can find a full list of supported emojis on this cheat sheet.
As well as those listed on the cheat sheet, traditional short emojis such as :) and :( are also supported.
For more information see: Markdown in Teamwork Chat