Buttock-clenching

1 Noun. The clenching of the Gluteus Maximus.
2 Adj. A word used to describe a tense, awkward or painful moment. This word was used by Bear Grylls whilst making a dangerous descent down a rock cliff in Man Vs Wild.

Buttock-clenching is a phrase used by British people.

1 Buttock-clenching helps strengthen the Gluteus Maximus.
2 That fall looked buttock-clenchingly painful.

buttocks clenched

When one does the clenching of the buttocks. In embarassment or fear.

Agatha's buttocks clenched.