As I was growing up, my family had a couple of sayings I took for granted were universal, at least within my language. As I became an adult I have learned that these are not universal at all:
the ketchup effect. It is an expression meaning that when things arrive, they all arrive at the same time. Think of an old school glass ketchup bottle. When you hit the bottom of it, first there is nothing, then there is nothing and then the entire content is on your food.
faster than Jesus slid down the mount of olives. Basically a saying that implies that the mount of olives is slippery due to olive oil and Jesus slipped.
What you lack in memory, your legs suffer. An expression meaning that when you are forgetful, you usually need to run back and thus your legs suffer.
My family too. They really looked down on cursing but shit was the exception. I remember my mom getting mad at young teenage me for saying "how the hell do you get this thing off" but if I'd said "this is bullshit" it would have been fine.
Another classic. I had never heard her say fuck until she was so mad at me she said it. Then she became even more furious because I made her say it.