Profanity

These crazy kids keep telling on each other for using vulgar language. Last night we had a conversation regarding a bad word that Gavin may or may not have used. It went something like this:

L-Mommy, Gavin said the "s" word today.
Me-Gavin, is that true?
G-No.
L-Yes you did, Gavin.
Me- Didn't you tell on Emma yesterday for using the "s" word? (word in reference here is stupid)
G-I didn't say it.
L-You said the "s-w-" word.

Gavin got really quiet and looked down, seeming totally guilty and ashamed, almost ready to cry. All the while, I was a little confused. I was searching my brain for what the word could possibly be, and could not for the life of me figure it out.

Me- I have no idea what word you're talking about.
L-It starts with s-w
Me-I'm still not following you.
L (whispers as she spells)- s-w-a-r-e
Me- What? He said the word "swear?"
L- yes, like, "I swear.."
Me- That's not really a bad word. Also, it's s-w-e-a-r. But, just to clarify, if you know a word is a bad word, don't use it. If you think it's a bad word, don't use it. If you're not sure whether or not it's a bad word, don't use it.

This morning, Emma was talking to Mike.

E-Daddy, Jonna says the "f" word at school. And so does Jaylon.
Mike- Really.
E- Yeah. It starts with an "f" and ends with "art"