When he's telling a story that strikes him (but not always those to whom he's telling the story) as especially funny, his normal laugh raises a few octaves to a high-pitched giggle! Even funnier is when my brother, Bruce (almost as manly as his father) starts laughing at Daddy's laugh. Bruce's laugh progresses from a deep manly laugh to a higher pitched "whoo-whoo", to a silent struggle to breath. I've actually seen him start to turn blue! This, of course, leads everyone else in the family in to deep belly laughs.
In my family, we don't need to exercise. Laughing is an aerobic experience.