«ضِحْكُوا عَ السَّقَّا حَسَبُهْ مِن حَقَّا»

The saying pokes fun at a gullible person; the water-carrier appears mainly for the rhyme, not as a judgment on his trade. Others spin a story or play a joke at his expense for amusement, but he misses the mischief and accepts every word as sincere, unable to tell jest from a real claim.

More broadly, it labels anyone who believes whatever they are told. It warns, half in jest, that excessive trust invites people to exploit you for sport, and it gently mocks the habit of never pausing to question an implausible account.

Use it, usually teasingly, about someone who swallows a prank, a tall tale, or an obvious leg-pull without question. It suits informal talk among people who know the victim, never to belittle a trade, and can sound condescending if aimed at a stranger or said to someone's face.