From Longman Dictionary of Contemporary Englishflex your musclesflex your musclesSHOW OFFto show your ability to do something, especially your skill or power The role will allow her to flex her acting muscles. → flex
Examples from the Corpus
flex your muscles• This new position should give you the chance to really flex your muscles.• He seized a horrible pair of forceps and I closed my eyes as he started flexing his muscles.• If you want to be an entrepreneur, you have to flex your muscles.• Read in studio Finally tonight we're going to flex our muscles.• This is an unfamiliar luxury for Labour voters; now they want to flex their muscles.• Soldiers, who previously had lacked social status, were now flexing their muscles because the military ran the country.• Harold was flexing his muscles for the perfect balance, teeth bared, knife poised over his head.• At the same time, it was beginning to flex its muscles on the world stage.• Like Querelle, men in tatty soiled uniforms are flexing their muscles, while others stare vacantly into the middle distance. 