My [36F] boyfriend [34M] makes up his own stupid folk sayings and it’s driving me crazy

Reposting because I forgot the tldr the first time.

My boyfriend Steve is always dropping his own versions of folksy wisdom into conversations, and they are almost always crude and dumb. This didn’t used to bother me, but after three years it’s wearing thin. I used to think they were kind of cute, like when he said absinthe makes the heart grow fonder after I told him I loved him at a bar in New Orleans, but most of the time they don’t even make sense.

They’re usually just dirty words swapped in to the real thing. “A sixty-nine saves time!” “The ass is always cleaner on the other side of the fence.” “A dick in the hand is worth two in your bush.” What does that even mean? If the object is to get dicks, two in my bush is obviously better.

During a completely serious conversation where I was agonizing over a painful choice, he said “Hey, you can’t make a mule without humping a few donkeys.”

It’s embarrassing. He says this stuff when we’re alone. He says it in front of friends. He says it in front of my parents. I’ve stopped laughing or even responding. I’ve asked him to tone it down. I don’t think he’s even aware that he’s doing it a lot of the time. He never uses the “real” sayings. Is there a service you can subscribe to where they text you new dirty versions of old proverbs every morning?

I’m at the end of my rope. I don’t know how to address it. I feel like a jerk arguing with him about it because it’s so ridiculous. A lot of people find it funny, but they don’t live with him! I don’t know if I can spend the rest of my life with a man who says things like “a fart at the beach is like Christmas in July”.

tl;dr Boyfriend makes up crude fake folk wisdom sayings and uses them all the time instead of the real things