something or someone that causes continuous trouble or annoyance
継続的な問題や不快を引き起こす何かまたは誰か (keizokuteki na mondai ya fukai o hikiokosu nanika matawa dareka)
"The new regulations have been a thorn in the flesh for small business owners."
"新しい規制は小規模なビジネスオーナーにとって肉体の棘となっている。" (Atarashī kisei wa shōkibo na bijinesu ōnā ni totte **nikutai no toge** to natte iru.)
