Select "Settings" from main lobby
Select "Game display"
Select "Show observer's messages" - make sure the box is ticked
Select "Apply"
Select "Save and close"
Hope that helps. If not, report back here and I do some screenshots for you.
I have only seen it used by fish to express their anger and frustration after being eliminated from a tournament. Its pretty pathetic to be honest. If you are out, then just let it go and move on