«يُصَفِّقُ بِيَدَيْهِ وَيُخَالِفُ بَيْنَ رِجْلَيْهِ وَيُغَرِّدُ بِمِلْءِ شِدْقَيْهِ»
He clapped his hands, moved his feet alternately and sang at full voice.
Yuṣaffiq / yukhālif / yugharrid are present-tense verbs whose sequence conveys ongoing action. Shidq refers to the side of the mouth or jaw.
The contrast is comic: the figure who had presented himself as restrained and destitute in court is now celebrating with exuberance.