I had a few people tell me how much they love the story of the missionary trying to say "Job" and inadvertently dropping the F-Bomb in a discussion. It reminded me of a certain lesson I taught for the language lesson in district meetings at the end of my mission. It was a lesson on profanity. I knew so many missionaries who had accidentally profaned on several occasions that it seemed a lesson dedicated to it would be useful. It pretty much amounted to me telling these stories.
A young missionary was trying to teach about prophets. He said: "God speaks to prophets and He says: 'Blah blah blah blah blah' and then the prophets say that to the people." He said this all in Russian except the "blah's." Everyone's eyes got really large. Turns out that blah sounds almost identical to profanity that is analogous to using the F-word as an interjection.
Another missionary friend was trying to say that we baptize people in water. In Russian water is 'voda' but to say 'in water' you say 'vo vodye.' The end of the word changes depending on the case and preposition. The missionary in attempting to say this added the incorrect ending and said 'vodu' or 'v adu' which means "in hell." Yes, he said 'we baptize people in hell.' (I guess as Mormons it's not too far off)
Often in Russian before people leave to go somewhere they say "we went." This once led to inadvertent profanity. In Russian there's no real syntax. Every word is "declined" much like verbs are conjugated. As a result, syntax is largely unnecessary. This means that you can speak like Yoda all the time and it's totally normal. If someone is leaving you might say "you went" to them. In russian that's ты пошел. If you decide to mix it up, it's still technically correct, but turns out that in russian that means F@$% you. Google translate actually does this translation correctly. Once when I gave this story in the profanity lesson one of the female missionaries got this shocked and offended look and said "That's what that guy said!" Apparently she'd been wondering why the guy slamming the door in her face told her that she'd left.
In Ukraine I picked up one of the Harry Potter books to read in Russian. In Russian he's known as "Garry Potter." This is because Harry is a bad word. It's an adjective form of a swear word for the male anatomy. It was always funny hearing new missionaries screw this one up.
Once after some people showed us some of their favorite cartoons growing up, we mentioned some of our favorite cartoons from our childhood. One missionary mentioned the names of the lovable cartoon ducks Huey Duey and Louie. Saying those names with a Russian accent is a bad idea. I don't believe Louie means anything. Duey sounds like saying "blow," (specifically saying 'blow' in command form). Huey is profanity meaning part of the male anatomy, but it's offensiveness is on par with our F-bomb.
This isn't even half of such stories, more to come later...