Squint if it helps. Play with your fear mentally. Imagine it's a golf ball and give it your best whack. Unlimited Power, Anthony Robins 13. Misspeak yourself and mishear others-intentionally for some funny repartee.
Nothing is funnier than in the moment real life humor.
Use universal topics for material. The more common the experience the more laughter. Give yourself time and give no humor before its time. Get better with practice and timing. These tips are chapters in my forthcoming book.