This is the 3377th most frequent Catalan word.
bunyol
A "bunyol" is a fritter or doughnut-like pastry.
Here, 'bunyol' refers to a type of fried pastry or fritter, typically sweet, consumed as a treat.
He menjat un bon bunyol a la pastisseria.
I ate a good fritter at the bakery.
In this context, 'bunyol' is used colloquially to mean 'mess' or something poorly done.
Aquest examen és un bunyol; té moltes errades!
This exam is a mess; it has many errors!
Again, 'bunyols' refers to the food, demonstrating the cultural aspect of preparing them as a homemade item.