«وَضَحِكَ حَتَّى تَغَرْغَرَتْ مُقْلَتَاهُ بِالدُّمُوعِ»
He laughed until tears filled his eyes.
Muqlatāhu is a dual form meaning his two eyes, and tagharg(h)arat describes liquid welling up. These tears come from laughter rather than the sorrow claimed earlier.
That reversal is central to the maqāmah’s irony: the same figure whose speech had evoked grief about a lost child now weeps with amusement at his own successful deception.