Guild Lurking

Guilds with the feature PREVIEW_ENABLED can be "lurked" in/previewed before actually joining. This is basically the same as joining except you are granted no permissions and are not counted as a member

Start Lurking

PUT /guilds/{guild.id}/members/@me?lurker=true&session_id={session.id}
Session ID is presumably the one found in the READY gateway message and you will be removed when this session expires
Returns a guild object

Stop Lurking

Same as Leave Guild