When my daughter was barely two years old, she dropped a favored toy in the kitchen and muttered an exasperated "dammit!" under her breath. It was dead-on perfect delivery--appropriate to the situation and not too loud. It may have sounded exactly like a certain other female in our house sounds when she drops stuff in the kitchen.
I never said a word to her about it then or any other time I've heard her do it. For one thing, I didn't want to make it seem exciting and forbidden. Mostly, I let it go because she was using it in an appropriate way. I never heard a sing-song "dammit dammit dammit" nor heard her shouting it for fun. I haven't been told she's used it at school, so for now I'm still in the clear.
See, not all curse words are created equal. To me, a shit or dammit muttered under your breath in frustration is really not the end of the world. It feels good. It's satisfying. I even read that cursing in response to pain has been proven to lessen pain. Those are not dirty words. They do not refer to body parts, they do not demean anyone, they are not delivered toward another in anger. Most of the really bad ones do one or more of those things. When the same little girl now loses her temper and screams dammit at me, that's a whole different ball of wax and cause for immediate room imprisonment, but if I hear her screw up or drop something, a quiet dammit is just fine.
I'm a country music fan, and my daughter and I have been on a Zac Brown Brand kick lately. For one entire weekend, I heard her singing that she wanted to have her toes in the water, her ass in the sand and a cold beer in her hand. I was amused, not concerned. In that context, ass is ok with me too. Frankly, I discourage my children's use of butt , and ass falls into pretty much the same category for me. However, when I heard my kids saying ass while on the swing set the other day, clearly just to be able to say a bad word, or even if I hear them singing a song just to say the word (the giggles give them away), then I stop it. It's all about context, and shouting bad words for all the neighbors to hear is not the context we're going for.
I don't listen to pop music on the radio, so the kids aren't exposed to much new music. When we were visiting friends recently, some older kids played "Sexy and I Know It." I confess I've probably never heard the song and don't know the lyrics, but I refused my kids' request to download the song (and claimed ignorance as to the meaning of LMFAO). They had already spent two weeks tossing around sexy and I didn't feel the need to further encourage it. I do not see the need to introduce anything remotely sexualized. It's certainly going to happen soon enough, and I do not need to be the one bringing it into their lives. To me, that is vastly more a concern than a few bad words.
I'm not sure what kind of mother it makes me that I'll let my kids curse within certain restricted boundaries but won't let them listen to top pop songs, but that's who I am. Cursing is just bad words. Sexy is about sex and trying to look a certain way so others value you in that way, and that is much worse for young kids in my opinion. So, in case you're confused, a review:
cursing to yourself in pain or frustration
cursing along with Mommy's redneck music
cursing at people in anger, especially Mommy
vulgar body part names
cursing just to get away with something