This is anicent history, but back in college I dated a girl who was sarcastic and funny at the same time. When the movie Love Story (a soapy, sappy tear-jerker) came out, we made a pact to wait for the most dramatic part of the show, and then laugh out loud. When the moment came, I nudged her and whispered “Now!” Her response was to punch me in the arm and go “Shhhh!”
So what do you do? Keep your mouth shut. It will be over soon.