When I was growing up, I never heard my mom swear. She was the type that would say in a moment of frustration "Oh, dang!" or "Geez!" and would even give us the evil eye if we said "Oh my GOD" as that was taking the Lord's name in vain, and we better not have dared to say "Goddamnit." She still holds a grudge against Eddie Murphy because she somehow saw a comedy special of his in the 80s where "every other word was the F-word".
So nowadays, I think it's hilarious to hear my mom swear. It's sort of like she tried to shelter me so much that I feel like sheltering her now, like she doesn't know that these words even exist. But she's come around quite a bit and will allow herself to occasionally say "shit" or "bitch" and has even been known (in rare circumstances) to drop the f-bomb - in a hushed voice of course.
Now my guy on the other hand, grew up in a family where swearing was okay. One of my favorite stories was about how when he was in elementary school, his mom got a call from the principal because her son had said "fuck". As it was more common at the time, they were going to give him some sort of corporal punishment. I don't know if it was with a paddle or what. But they called his mom first, who responded with "you're not going to lay a fucking finger on my kid!" and came to pick him up. Yay mom! Fuckin A!
Still, even now I cringe if he happens to swear or say anything inappropriate in front of my mom. His humor is great, I love it, and it's never anything directed at her or said in anger, but... I nearly died when he was telling her about the show Deadwood and how they say "cocksucker" all the time. The word cocksucker came up about 5 times in that conversation and led me to give him a fierce elbowing when she wasn't looking. But my mom laughed and everything, so maybe it's okay as long as he's saying it and not me. Maybe he's trying to test her. The other day she was commenting on a restaurant that was called BD's grill or something and she said she wondered what the BD stood for. He says "I'm guessing it's not bondage & discipline" which was funny but again, I wanted to be swallowed up into the ground. She laughed though. I guess now I'm the prude.