YouTube has a set of emoji-like emotes which work in live streams and compliment the standard set of emojis which can be entered using shortcodes.

These include the YouTube logo which can be entered by typing :yt: into any live chat.

Emotes on YouTube do not work in YouTube captions or comments, and these will convert to the text string when copied outside of live stream chats.

:buffering:
:oops:
:yt:

New YouTube emotes for Coronavirus were released in March 2020 include:

:chillwcat:
:chillwdog:
:dothefive:
:elbowbump:
:elbowcough:
:goodvibes:
:hydrate:
:learning:
:sanitizer:
:shelterin:
:socialdist:
:stayhome:
:takeout:
:thanksdoc:
:videocall:
:virtualhug:
:washhands:
:yougotthis:

Hidden codes which don't appear in the emoji picker, unless the code is typed:

:awesome:
:gar:
:jakepeter: -> in memory of Jake Peter
:wormOrangeGreen:
:wormRedBlue:
:wormYellowRed:
:ytg: