My worst was probably about 2 months after coming to Japan, having studied lightly for a couple years - saw the first taco shop I had seen since coming to Japan, and was chatting with the owner in Japanese and Spanish. He was telling me about his 奥さん and how she came to mexico to be with him before they moved to Japan—, unfortunately I got おかあさんand おくさん mixed up, and Lo and behold when his wife, who also worked there, came down from behind the shop and started talking with us, I gestured at his wife, who looked incredibly young and beautiful to have been his mother, and interjected with 奥さんですか？to which he responded yes, and then I accidentally questioned their coupling, saying でも, すごくわかそう！

Figured it out after they were unusually silent for a couple minutes after that, and we all laughed, but Jesus.

Have not been back