probably funny just to me.
Tonight in beginners class I taught, among other things, ai dori kote gaeshi, and after demonstrating the throw to one pair, I noticed that uke's upper foot was twitching spasmodically.
"...are you... your foot..." I looked at his face, and back to the foot. The twitching paused. "I'm fine," he said. The twitching started up again. At this point I started giggling uncontrollably, let go of uke, backed away, tried to get a hold of myself... and kept on giggling. I finally had to go blow my nose because my eyes were watering.
Everyone else in the dojo was definitely laughing (gently)at me, not with me.
I don't know why it seemed so hilarious, but it was fun anyway.