Don't Worry, Mom

Last week the girls were playing outside and I had the back door open while I was fixing them lunch. Out of nowhere, I heard Jessilyn scream, "Ooooooh my Goooddddddd!" (d sound emphasized) I felt my blood immediately begin to broil. I calmly said, "Jessilyn, please come here." The following conversation proceeded like this:

Me: "What did you just say?"
Jess: "What Mom?" (with a completely innocent/oblivious face)
Me: "What did you just say?"
Jess: "Don't worry, Mom. I said 'Oh my Goddddd, not Oh my gosh'." (not sure about the
double quotation rules...my English teacher would be so proud...)

We have always told Jessilyn that we don't say "Oh my gosh," but we've never explained the reasoning behind the rule. Obviously, it was time to do some explaining!