a bag full of twat
A bag full of twat is someone who’s so stupid it’s like they were made by a twat and stuffed into a bag.
My friend’s kid is a bag full of twat. He thinks clouds are made of cotton candy.
My brother-in-law is a bag full of twat. He thinks the internet is a type of soup.
My friend’s dog is a bag full of twat. It howls at the mail truck.