When Sid's Dad tells him a really funny joke, Sid laughs so hard that his face hurts. Sid wonders why his face would hurt if the joke was funny? When Sid and his friends investigate at school, they learn that they have muscles all over their bodies, even in their faces!
Visit the Website: http://pbskids.org/sid/
Episode #137 / Length: 28 minutes
On TV
Tuesday, April 16th at 10:30 AM on KLRU
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