Yawn
Yawning
noun, verbal noun
When you lack stretching, your body has to get that energy out somehow, so you end up yawning.
The reading for this is an exception. Here's a mnemonic to help you:
You've never seen more yawning than when you performed acupuncture (あく) on a bee (び). It was so relaxed from being the one poked for once that it just couldn't stop yawning.
退屈すぎて欠伸が出てきた。
It was too boring and I yawned.