Why is an actor's unintentional giggling called a 'corpse'? It seems to me quite the opposite. It proves that he's very much alive, and can still tell how silly this all is: him dressed up as someone else speaking words written by a third party.

Why is an actor's unintentional giggling called a 'corpse'? It seems to me quite the opposite. It proves that he's very much alive, and can still tell how silly this all is: him dressed up as someone else speaking words written by a third party.