Used almost exclusively in the compound 尥蹶子 - literally 'to throw out the hooves backward', the gesture of a stubborn horse, donkey or mule. By extension it means a person 'throwing a tantrum / kicking back' against authority. Vivid, colloquial, and slightly rural / northern in flavor.
memory
Picture the radical: 尢 is a person with bent legs. The phonetic 勺 (ladle) on the right gives the sound. Together: a bent-legged scoop of energy lashing out - a buck-kick.