This classic old George Carlin bit sums up one of the things I love most about both Catholicism and Judaism: both have a concern with rules that gives them a huge capacity for generating convoluted questions and answers. They approach questions with very different methods, and take them in different directions, but Thomists and Talmudists both make a meal of them.
A rare case where both took a similar approach to a very stupid question is, of course, the barnacle goose, whose medieval legend reads like a version of the famous Canadian house hippo PSA: the Irish felt that since the birds grew from barnacles or maybe from trees (seems legit) they were technically fish, and therefore okay to eat on Fridays. Sed contra est:
…Bishops and religious men (viri religiosi) in some parts of Ireland do not scruple to dine off these birds at the time of fasting, because they are not flesh nor born of flesh…. But in so doing they are led into sin. For if anyone were to eat of the leg of our first parent (Adam) although he was not born of flesh, that person could not be adjudged innocent of eating meat.
I admire this effort, but it’s only partially convincing. Rabbis, meanwhile, were trying to determine if the birds were kosher. From what I read it seems like there was some appropriate scepticism: “birds growing on trees, if it be true they grow on trees, are not forbidden food.” Another rabbi declared that since they grew from barnacles they were shellfish and therefore treif, thus agreeing with the categorization of the Irish clerics.
I guess I could draw some larger epistemological point from all this (perhaps that legal reasoning isn’t very useful when your science is shit) but really I just find the barnacle goose delightful.