After you mess up in front of everyone, laughing at yourself first takes their power to mock you.

Mockery works by revealing something you were trying to hide. Saying it first removes the material, since there is nothing left to expose and no reaction to collect, and most people lose interest within a minute. It also tells the room you are not frightened of the thing, which is usually what was being tested.

The next time you get it wrong in front of everybody, say something short and dry about it and carry on. Keep it light rather than bitter, because self-attack reads differently and invites more. One sentence is plenty, and the carrying on is the part that works.