プログレッシブ和英中辞典(第4版)の解説
かたひじ【肩肘】
肩肘張った付き合いはよそう
〔堅苦しく〕Let's stop acting so formally toward(s) each other.／〔用心して〕Let's stop being so leery of each other.／〔対抗して〕Let's stop trying to outdo each other.
肩肘張って生きているが，実は寂しがり屋だ
「He pretends to be strong and independent [He puts on a bold front], but actually he gets lonely very easily.
彼らには肩肘張ったところがない
They behave quite naturally.